Angels
Angels are a popular theme in Magic, but are usually rare or hard to find. Angels are mostly white-alligned, however with the release of the Conflux expansion, Maelstrom Archangel was a five-colored Angel. It was also popular in the Shards of Alara block to see green, white, and blue Angels from the Shard of Bant. Also, in the Alara Reborn set, Filigree Angel was a white and blue artifact creature.
The most known Angel in Magic is Akroma, Angel of Wrath. Released in the Onslaught expansion, Akroma was created by master illusionist Ixidor to fight Phage the Untouchable and the Cabal. Akroma was destroyed when she and Phage were cut down by the barbarian Kamahl. The two women then fused together to create Karona.
In an alternate Dominaria, Ixidor was more of a mad man, and created Akroma, Angel of Fury. This Akroma was red-alligned, but was considered worse that Akroma, Angel of Wrath.
There is also an angel from the Shadowmoor set, called Twilight Shepherd. Although no angels were thought to exist on Shadowmoor, this is the only angel in the set and the block.
There was also a card featured in the Divine VS Demonic Duel Deck compilation and Seventh Edition set called Fallen Angel, which was black-alligned.
Anurid
Frog-like beasts of Otaria's forests. Anurids show some signs of limited sentience. Most of their kind scavenge the forest floor while others feed on airborne prey using their long, darting tongues.
In the Odyssey storyline, Ambassador Laquatus's bodyguard was a mind-controlled Anurid named Turg. Sadly, Turg met his end in a fight against a giant squid during an attack on Emperor Aboshan.
Atog
Small imp-like creatures that grow by feeding on various things to gain the necessary nutrition to grow. In the game, this ability is symbolized by the sacrifice of a resource to give the creature a temporary boost in power/toughness.
The original Atog was much maligned when first released, due to his ability requiring an artifact being sacrificed. After a few years its ability as an effective creature was noticed. The blue, turn-eating Chronatog was used as a combo piece in Stasis decks, while the Blue/Black Psychatog (which eats both cards in a player's hand and cards previously played) dominated tournament scenes with its inclusion in slow control decks.
The word 'Atog' is an anagram of 'Goat', and the atog is a parody of a goat's tendency to eat whatever it comes across. Some say that the name actually originates from a contraction of "Artifact to graveyard", but this may be a Backronym.
Aven
A race of bird people, Aven can be found on the Dominarian continent of Otaria, but are not native to Dominaria itself. Majestic and proud, the Aven are also agile and fierce. Master warriors and tacticians, most Aven lend their services to the Order. Their society is very militaristic in organization, usually with a high position commanding the highest respect in an area. The last known Aven of rank was Commander Eesha who commanded the Northern Order, after Captain Pianna (create) and Major Teroh were killed. It is unclear who leads the remaining Avens during the events of Time Spiral - though Avens play no real part in that story line and are featured in only a few cards of the corresponding expansion set. The leader of the Order changed numerous time throughout the time line of the Otaria story where each leader tends to be either killed by the Mirari or simply dies in combat out of their own suicidal zeal reflected in their cards.
Aven can also be found on the Bant shard of Alara, where they are sparse but highly respected for their proximity to angels. The Grixis shard, however, is the only known place where the vulture-like Kathari are found. The Kathari are seen as a sub-species of the Aven.
In the card game, there is no Aven creature type. Aven instead have the Bird creature type and at least one other creature type, most commonly Soldier.
Cat Warrior
Cat Warriors (and Panther Warriors) are catlike humanoids. The mightiest of the Cat Warriors was Jedit Ojanen. Others include Mirri of the Weatherlight (create) and Purraj of Urborg.
Cephalid
Cephalids are octopus-like beings that live in the depths of the oceans surrounding the continent of Otaria.
Cytoplast
Cytoplasts are a Simic creation that can absorb and transfer a host's DNA to other hosts. They appear as blue-green blobs. Originally, they required a host's consent for surgical attachment, but Momir Vig developed them further so they could attach instantly to a host. Cytoplasts take a small amount of energy from their host, but also greatly enhance its physical and/or mental capabilities. In the card game, Cytoplasts are represented by +1/+1 counters. Cytoplasts can be seen on the cards Simic Basilisk and Cytoplast Manipulator.
Demons
Demons, like Angels and Dragons, is a popular Magic theme. They are usually black aligned, such as Lord of the Pit.
As of the Shards of Alara Block, a card named Prince of Thralls was released. Unlike most Demons, Prince of Thralls is blue, black and red. Other Demons in the Shards of Alara block included Extractor Demon, Malfegor, Defiler of Souls, and many more.
In the Zendikar set, a Demon named Ob Nixilis, the Fallen was released. The flavor text speculates that Ob Nixilis was a planeswalker. Ob Nixilis is also famous for Zendikar's famous Landfall mechanic.
Dragons
Winged giant reptilian beasts of great destructive power, dragons are a staple in any fantasy genre. Many different dragons exist, along with great legendary dragons. In the worlds of Magic, the primeval dragons Treva, Rith, Darigaaz, Crosis, and Dromar were dragons that once ruled the world. They were tricked by humanity and were sent to sleep. The elder dragons Arcades Sabboth, Chromium, Nicol Bolas, Palladia-Mors and Vaevictis Asmadia (create) once were powerful planeswalkers. They fought a large war entitled the War of the Wyrms or the Elder Dragon Wars. They lost their spark when a powerful world spell cast all other dragons to the land, creating the elder land wyrms. The five fold council fell apart and warred against each other, finding themselves chained by planeswalkers. Only Nicol Bolas has survived with his spark.
Most dragons are red aligned, and almost all are able to fly.
Drake
Quick, agile creatures, Drakes are small relatives of Dragons. They generally live near the coastline, which leads to the idea that they feed on fish and other aquatic creatures. They generally lack forearms, as they have been modified into wings.
Elf
Eldrazi
The Eldrazi are ancient and powerful creatures, native to the Blind Eternities. They have neither physical form nor color alingment, and althought they have only been seen in Zendikar, the plane serves only as a prison to them. They are also known for their distinct ability of Annihilator which is the ability to attack and remove Permanents from your opponents' side of the field.
The most famous and powerful of the Eldrazi is "Emrakul, the Aeons Torn".
Goblin
Griffin
Griffins are wild creatures that share the characteristics of both lions and eagles (or felines and birds of prey). They inhabit wide prairies, cliffs and canyons. Usually white, flying 2/2 creatures, they are fierce fighters, often with initiative, but not too powerful. Not being intelligent creatures, they are commonly used for mounts by knights and paladins, if these are able enough to tame them (tough job).
Homarid
Homarids are lobsterlike enemies of the Vodalian Empire that began to thrive in the new climate after the Brothers' War. Young homarids are known as Camarids (crayfish). In Terisiare their descendants are known as Viscerids.
Imp
Imps are pesky, usually winged creatures resembling very small devils. Usually black, imps have been a part of the game since its inception, with Nettling Imp in Alpha. Nettling Imp lacked the ability to fly, which is common to almost all its brethren.
Indrik
Indriks are huge mammals, native to the plane of Ravnica. Indriks are so heavy that they can squash Mizzium-- a magically strengthened metal-- underfoot. Indriks can also emit a howl that disturbs certain spells and artifacts.
The name of the Indrik is based on the mythological Russian Indrik, the king of beasts, and its appearance is modeled after the real-life prehistoric Indricotherium.
Jhovall
Large, six-legged predatory cats native to Mercadia. They are used as mounts by both Mercadian and Ramosian soldiers. They appear to be native to the barren fields surrounding Mercadia City but are encroaching into the Deepwood forest, displacing the predators that already dwell there, such as the wolverine.
Kavu
Kavu are enormous lizards, created by Gaea to defend the Yavimaya forest during the Phyrexian Invasion. Multani, a Maro-Sorcerer, as well as a member of the Weatherlight crew, awakened them by praying to the goddess Gaea at Mori Tumulus. The Kavu were efficient and powerful allies to the defenders of Dominaria, because of their thirst for Phyrexian flesh. They were spread throughout Dominaria by sleeping in the boughs and branches of the Magnigoth Treefolk as they traveled the world in search of their escaped captive, Rith the Awakener.
The only Kavu that appeared outside the Invasion block are Rogue Kavu, Kavu Climber, and Firemaw Kavu. Rogue Kavu and Kavu Climber were reprinted in 9th edition, and Firemaw Kavu was printed in Time Spiral.
Kithkin
A quick and agile humanoid or elflike species, which used to live in Amrou Haven. They also reside in Lorwyn-Shadowmoor.
Leonin
The Leonin are a proud race of Lionfolk that reside in Mirrodin's Razor Fields. Led by a kha, from the ancient den, Taj-Nar (create), the Leonin are constantly in conflict with the undead nim of Mephidross. The males engage in combat, while the females hunt and raise the young. While engaged in combat, Leonin are brave and chivalrous, never backing down from a challenge, and never resorting to underhanded trickery. While Leonin are not engaged in war, they commonly train. When they are not training, Leonin can often be found hunting or holding ritualistic celebrations. (dandwiki.com)
The Leonin are led by Raksha Golden Cub, a noble warrior. Roles in society are generally separated by gender. Male leonin are generally soldiers, craftsman and priests, whereas females are generally healers, hunters and the Pteron-riding Skyhunters.
The planeswalker Ajani Goldmane is a leonin.
Lhurgoyf
Large monsters that developed during Dominaria's Ice Age, Lhurgoyf are monstrous scavengers. They possess two specialized fangs developed for pulling corpses from the ground. They lay incredibly hard eggs, which are mistaken for gemstones by unfortunate travelers.
The flavor text on the original card is infamous in magic lore, spawning not only a reference on Revenant's flavor text, but also a short story explaining the flavor text in the Monsters of Magic anthology and its own card in Magic's second humor expansion, Unhinged, as well as one of the quote's speaker in Time Spiral.
A Lhurgoyf's power and toughnesses are directly proportional to the amount of a certain type of card in each player's graveyard, such as creature cards for the original Lhurgoyf.
Licid
Symbiotic creatures found in Rath, Licids may be natural creatures or twisted versions of a Dominarian species; they've changed too much to be sure. Like some species of beetle, the Licids are capable of snapping their bodies to jump several times their own body length to land on a host organism. When latched on, the Licid's legs dissolve into the host and the two creatures bond together. While the Licid is latched on to a host, the host either gains attributes of the Licid or is hindered by it. When Licids leave their host they leap off, leaving no physical trace.
Licids are among the most confusing types of cards, rules wise. This is due to the fact that to symbolize their symbiotic nature, they become Auras.
Loxodon
Elephant-folk that live in the Razor Fields of Mirrodin, presumably named after the African elephant, Loxodonta africana. Not too much is known about them. Stalwart and strong, according to the flavor text of Loxodon Stalwart, "the Auriok tribe once tried peace with the Loxodon, while the Leonin once tried war. Neither succeeded."
Loxodon are large creatures with combat-oriented abilities, frequently including trample. They were seldom played in tournaments due to there being cheaper, more efficient creatures to use in the environment.
The Loxodon race were also discovered settling in the ecumenopolis plane Ravnica.
Note: It is possible that the Loxodon are developed from the 1st and 2nd edition Dungeons and Dragons creatures, the Loxo, a race of two-trunked anthropomorphic elephants.
Lupul
A creature made of maggotlike worms. They have the ability to disguise themselves as any other creature they see. Usually though they take the shape of their last humanoid meal. The Boros Angels thought they had killed all of these creatures, however a small colony survived and served under the House Dimir Lord, Szadek. Lupul is the Old Ravi word for "Lurker". Probably represented in the game by the cards Dimir Doppelganger and possibly Mindleech Mass.
Maro
Nature spirits of forests, Maro create their physical bodies from living plants. Every major forest has one particular Maro-Sorcerer. This spirit is the embodiment of the forest's lifeforce. The name Maro originated from the name Mark Rosewater, the current head Magic Designer (in fact, he designed the aforementioned card quite a while before he came to Wizards of the Coast). Originally, the first two letters of the first and last name of an employee with an email address at wizards.com was used for individual email, making Rosewater's "MaRo".
A famous Maro mentioned in Magic was Multani, Maro-Sorcerer, emissary of Yavimaya. He is a legendary untargetable creature that had power and toughness equal to the number of cards in all players' hands. This often makes him incredibly powerful, especially in Multiplayer games.
Five legendary kami from Saviors of Kamigawa, dubbed 'Ancestors' but more casually referred to as 'Maros', were inspired by the original Maro. Though their names end with 'maro', they are not Maros.
Merfolk
Merfolk, another common fantasy staple, are fairly abundant in Magic. Traditionally, they slither on the ground when not in water.
Otarian Merfolk
The merfolk of Otaria were few in number, and were under the command of Aboshan.
Rathi Merfolk
The Rootwater merfolk of Rath have become savage carnivores (with the help from some judicious genetic alteration by the evincars.)
Saprazzan Merfolk
The Saprazzan merfolk of Mercadia become legged on land, but some find it quicker to bring the water with them.
Vodalian Merfolk
The merfolk of Vodalia and Atlantis are an aquatic species who have long, almost eel-like bodies, humanoid faces and arms, and spinelike protrusions at the shoulders. Their scales form multicolored patterns and they are capable of changing colors and patterns at will. Red is a restricted color, used only by those who have gained favor with the empress Galina, and defines leadership and social status
Myr
Myr are the artificial constructs built by Memnarch that he used to observe the surroundings and inhabitants of Mirrodin.
The myr, in form and function, are modeled after ants, as is evidenced by not only their appearance in card art, but by the fact that "myrmex" in ancient Greek means "ant" and by the nature of most myr cards: small, low rarity creatures that do simple tasks that can really start to add up when more are gathered.
Nantuko
The Nantuko race are mantis-like druids native to the Krosan forest on the Dominarian continent of Otaria. They are lead by the primus, Thriss, who was said to have planted the first seeds of the forest after the Phyrexian Invasion had been ended. Wise and reserved, they're seldom seen by forest outsiders.
Nantuko filled the mana-production abilities made with the absence of Elves in Odyssey block, as well as the support abilities others provided, such as giving temporary boosts to creatures.
Nephilim
Gigantic and mysterious, grotesque creatures from Ravnica. They were imprisoned deep below the plane's surface, beneath the Undercity. When they were awakened by cultists, the sheer power they released caused havoc. They are represented in the game by 4-colored creatures with bizarre abilities.
The name "Nephilim" is taken from the biblical creature of the same name, first mentioned in the book of Genesis: chapter 6 verse 4.
Nezumi-bito
Ratfolk that dwell in the Takenuma swamp of Kamigawa, the Nezumi are greedy, treacherous thieves, mercenaries and bandits. Often involved with the Soratami. A few Nezumi are also talented shamans, their magics learned from scrolls stolen from the Minamo academy.
Nezumi are generally split in to various gangs, some more powerful than others. Like Goblin kingdoms, one can claim leadership assassinating the head of a clan. One legendary Nezumi, known as Marrow-Gnawer, assassinated the leaders of three gangs in one night, thus becoming leader of them all. One gang of note is the Okiba gang, a clan of treacherous ninja. Nezumi females give birth to multiple offspring, leading to each Nezumi having around forty to sixty siblings.
Their name comes from the Japanese 'nezumi' meaning 'rat' and 'bito' meaning 'person'.
Nightmare
The Nightmare is a black flying creature resembling a horse with flaming hooves whose strength is proportionate to the number of swamps the player has in play. "As the poisoned land spreads, so does the nightmare's rage and terrifying strength."
The term also refers to a breed of terrifying creatures commonly associated with Dementia summoners of the Cabal. A Dementia summoner would call forth the most terrible fears that lurked within the deepest recesses of their mind and though the use of black mana, grant physical form to these thoughts. The exact physical bodies varied from summoner to summoner, but in occasions when a nightmare was created, it would "replace" a physical object or creature in the real world, the removed object not returning until the monster was slain. The Dementia Master Chainer created some of the most terrible nightmares in history to serve the dark orders of the Cabal.
Nightstalkers
Magically created servants of the swamp queen Tojira (Portal Second Age). They ride large mechanical beasts. The Nightstalkers are also three creatures-- Urborg Panther, Feral Shadow, and Breathstealer -- that can be sacrificed to put into play the Spirit of the Night, an extremely large black legendary creature.
Nim
Quick, "natural" undead found in the Mephidross Swamp of Mirrodin. The Toxic Necrogen mists have a zombification effect on living creatures, most specifically the Moriok tribe of Humans. The Nim have cranial plating covering their faces as the necrogen causes metal buildup and loss of eyes (and therefore sight). They also expel their own necrogen from vents that erupt from their rotting skin. They are controlled by the warlord Geth and are constantly in conflict with the Auriok and Leonin of the Razor Plains as the Mephidross expands.
Orochi-bito
The Orochi are a race of lithe, four-armed snakefolk from Kamigawa's Jukai forest. A tribal society, there are at least three major tribes in the Jukai. The Matsu-tribe are a tribe of highly skilled archers, whose leader is never identified storywise. The Sakura-tribe is a tribe specializing in magic lead by the shaman, Sachi. To be a shaman, an Orochi must be hatched from an egg "touched by the Kami." The Kashi-tribe are warriors, led by Sosuke, Sachi's brother. Like their limbless cousins, the Kashi-tribe have a paralyzing venom used to subdue trespassers within the orochi territory.
A leader is mentioned on the cards, although over which tribe he rules is unknown. He is known as Seshiro, the Anointed. Considering that he is Sachi and Sosuke's father, he might be the leader of all the Orochi.
Their name comes from the Japanese 'orochi' meaning 'serpent' and 'bito' meaning 'person'.
Praetor
Praetors are extremely powerful cards introduced in New Phyrexia. They are similar in look to zombies or horrors, but they all look very different. Since the Praetors are a cycle, there is one of each color. Each has wild abilities that usually win the game on the spot. The five Praetors are Elesh Norn, Grand Cenobite, Vorinclex, Voice of Hunger, Jin-Gitaxias, Core Augur, Sheoldred, Whispering One, and Urabrask the Hidden.
Pteron
Flying reptilian beasts, that look very similar to the extinct pterosaurs, except with much stronger body build. They are used as mounts by the Leonin of Mirrodin. While only one card represents a Pteron, Pteron Ghost, they are featured in the artwork of several cards such as Leonin Skyhunter, Skyhunter Skirmisher and Skyhunter Cub.
Rats
Rats are filthy, detestable, often savage little creatures who inhabit most planes in Dominaria. Linked to the black mana, they often show swarm capabilities, benefitting from other Rats in play, especially if they are from the same species. They usually come with some destructive power too. The Kamigawa plane is inhabited by an entire race of Rat-folk (see Nezumi-bito). Most of them have an effect that effects the opponents hand.
Rootwalla
A breed of large lizard that has the ability to increase its strength temporarily. Rootwalla were originally meant to be Chuckwalla, a real world lizard. But when the art came in for the card it showed a made-up reptile instead.
Saproling
In natural environments and planes, Saprolings are carnivorous fungal creatures that look similar in appearance to worms. It is portrayed that they are capable of reproducing by Spontaneous Generation, though a few treefolk and thallid have the ability to create them as well.
Saprolings exist in the urban environments of Ravnica as well, resembling crystals enveloped in floral tendrils. Contrary to what some assume, Ravnican saprolings are functionally identical to natural saprolings, and their development in Ravnica was just how the Selesnya grew them. The Golgari card, Golgari Germination, features another form of saproling grown by the Golgari: one made partially out of the flesh of a dead creature.
Saprolings are known for the fact that they don't actually have any physical cards, but are portrayed through tokens created by cards.
Slith
The Slith are mysterious creatures from Mirrodin. They are born within Kuldotha, the Great Furnace, and only emerge when one of Mirrodin's suns are aligned overhead. As they emerge, the slith's attributes are set according to whatever sun was overhead. Afterwards they continually follow the motion of their aligned sun. They resemble hunched human forms with skull-like faces.
Slivers
Slivers are metamorphs that live in huge hive colonies. Slivers first appeared in the artificial plane of Rath, with a hive colony below Volrath's Stronghold. Whether these creatures were a creation of Volrath or were a natural species brought to Rath like so many others is unknown.
Venser exerts some control over the colony; he has constructed mechanical slivers which have been accepted into the hive. Slivers are unique in that they share adaptations. This is accomplished through a unique organ the slivers possess. It acts as a telepath node, allowing the slivers to transmit information to one another, but it also serves a much more unusual function: it acts as a gland, secreting chemicals into its bloodstream which in turn affect how its cells replicate genetic material. Apparently, slivers grow at a ridiculously fast rate, because these changes are almost spontaneously manifested. For instance, if a Sliver with wings comes within a certain distance of a sliver with firebreathing, both Slivers share their abilities, in that they can each use both abilities. Vicinity is very important, as they can't share these abilities over long distances.
During the Rathi overlay of Dominaria, the Sliver Colony was planeshifted into the heart of a volcano, destroying the Sliver Queen and any slivers within the hive. Around 100 years after the Phyrexian Invasion had ended, the body of a sliver was found near a volcano in Urborg. The Riptide project, a program designed to resurrect species driven to extinction during the invasion created by the cephalid Empress Llawan, succeeded in recreating a living sliver. Unfortunately, the Slivers proved to be too much for the Riptide researchers to handle and quickly overran the island, devouring every living thing they encountered and reproducing rapidly. Within weeks, more slivers nested on the continent of Otaria than had ever existed on Rath. Despite most of the slivers being destroyed when the false-goddess Karona was destroyed; many slivers survived, or at least enough to reproduce their numbers and mutate massively after the several centuries between Time Spiral and Scourge.
Slivers that survived the apocalypse caused by Karona's destruction and a few breeds that were "timeshifted" into the present by the violent upheavals of the time stream were one of the few creatures to flourish on the dying plane of Dominaria. As other species fought for survival in a world almost completely drained of mana, the slivers continued to multiply and mutate into new forms. Some of these new breeds mimicked traits of other life forms in the multiverse; the vampiric sliver fed upon the life essence of its prey and was strengthened in return, much like the dreaded Sengir clan and their ilk. The gemhide sliver adopted an ability similar to that of the fabled Birds of Paradise, creating mana of any color whenever it wished. Basal slivers possessed the innate drive to sacrifice themselves to provide for their nestmates, similar to the way the master breeders of the Ebon Hand used Basal Thrulls for their dark rituals. Another new strain present during this time was the shadow sliver, trapped between two worlds when the nest within the bowels of Volrath's Stronghold was overlaid on Urborg. Presumably, this breed was a terror to the il-Kor, il-Vec and il-Dal tribes who were also caught in the overlay in their home, the City of Traitors. Without the leadership of their queen, these sliver swarms raged across the plane, largely unstoppable when gathered in great enough numbers. The destruction caused by the slivers was not necessarily malevolent, the hive-minded creatures only sought a new queen, new leadership to guide their numbers. It is hinted that the planeswalker Freyalise sought to use this need to the advantage of the entire plane of Dominaria, whether or not she was successful has yet to be seen.
The Hivestone, a strange artifact discovered within the ruins of the Stronghold, was later found to have been used by the various evincars of Rath's past to control the seething sliver hive and its queen. Upon its rediscovery however, the device became a curse to its wielder, bending its possessor's will to the will of the swarm.
Soratami, or Moonfolk
Cloud-dwelling race of Kamigawa, the Soratami have constructed magnificent palaces in the sky. Until the years of the Kami War, the Soratami maintained almost absolute isolationism. During the Kami War, they have ambassadors sent to the Minamo school and Eiganjo Castle to help with the defense against the rampaging spirits. In reality the soratami manipulated the human leaders of both Minamo and Eiganjo into stealing an essential aspect of the O-Kagachi, the guardian spirit of the divide between the spirit world and the material world, in order to cause the O-Kagachi to manifest and destroy the great nation of Eiganjo headed by Konda. The soratami then planned to rule Kamigawa without the interference of Konda and the military might of Eiganjo. They also launched a major assault upon the Orochi-bito of the Jukai Forest in an attempt to eradicate a species they personally felt threatened by, due to their close spiritual contact to their patron spirit, the Myojin of Life's Web. The Soratami's own patron spirit, Mochi, the Kami of the Crescent Moon encouraged his followers to proceed with his plans of Kamigawa being ruled by the superior intellect of the Soratami. Both Mochi and the Soratami were ultimately foiled by the ochimusha Toshiro Umezawa and the terrifying power of the ogre Hidetsugu and his patron spirit, the All Consuming Oni of Chaos. Not much is known about Soratami society, though there appears to be very little unsightly matters. Soratami mages use mirrors often to perform their spells.
All the Moonfolk cards printed in the Kamigawa block fly and have abilities requiring the return of a number of their controller's lands to their hand in exchange for an effect. The legendary moonfolk wizard Meloku the Clouded Mirror is an extremely powerful, game-swinging card that has the ability to dominate games.
Their name comes from the Japanese 'sora' meaning 'sky' and 'tami' meaning 'race' or 'society'.
Spike
Leech-like creatures that were brought to the plane of Rath, Spikes are parasites. They are capable of leeching nutrients from other creatures in a manner similar to leeches.
Spikes have the distinction of being creatures with 0 for both power and toughness, but come into play with a number of +1/+1 counters on them which can be moved to other creatures or traded for other abilities, such as gaining life.
Spirit
See also Spirit.
Spirit Avatar
In the Shadowmoor and Eventide sets, there is a cycle of ten creatures known as the Spirit Avatars. (Spirit Avatar is also their creature types.) They are powerful hybrid creatures with powerful abilities, making them good to have in a dual-colored or monocolored deck. The most recognizable part of them is that they each have a converted mana cost of five, and each of the five mana symbols in each is a hybrid symbol that the creature represents. For example, Overbeing of Myth has a mana cost of five green-blue hybrid symbols. Each of the Spirit Avatars has a special weapon, and those weapons are shown on a cycle of ten enchantment cards between the Shadowmoor and Eventide sets. An example is Favor of the Overbeing, which is the Overbeing of Myth's special weapon. Each of the ten weapons give a creature a bonus depending on it's colors. If the creature is the same colors the weapon is, the creature gets more of a boost.
In the Shadowmoor storyline, the Spirit Avatars don't play much of a part, however each Spirit Avatar card has flavor text quoting the Seer's Parables. (The Seer's Parables is a collection of elvish stories.) The flavor text for each card is usually grim, and the Parables somewhat complain about having them. Interesting, though, is that the Spirit Avatar's names are all synonyms to the word demigod, with the exception of Ghastlord.
Thallid
Semi-sentient fungal creatures created by the elves of Sarpadia, Thallids were to be used as a food source. They were kept in check for a while before eventually the population increased dramatically, and they began overrunning the elves, along with Saprolings, which are produced by certain Thallid breeds. Supposedly, the elven nation of Havenwood is no more, destroyed by the thallids.
Thallids were featured specifically in the Fallen Empires expansion. Like most cards from the set, there were very few tournament-worthy cards, none in the Thallids' case, as their abilities needed to "charge" for an average of three turns before they could be used. To use the ability again, another three turns of charging would be required.
Thallids and their creature type, Fungus, did not appear again until the Time Spiral set, accompanied by their misguided creator, Thelon of Havenwood.
Thrull
Like the Thallids, thrulls were bred on Sarpadia. The Order of the Ebon Hand created them as fodder for sacrifice and slave labor. After this initial success, breeders such as the legendary and reviled Endrek Sahr continued to tinker with the form of the thrull, increasing intelligence and strength among other attributes. However, this turned out to be the Ebon Hand's undoing as the augmented Thrulls rebelled against their creators and eventually destroyed the order.
While relegated mainly to the Fallen Empires expansion, a few thrulls have shown up in subsequent sets. No thrulls have shown much Tournament play, although they are a favourite creature type among many players. Thrulls made a major return in the Guildpact expansion, as servants of the white and black Orzhov Syndicate. According to the flavor text on Mourning Thrull: During their ascent to spirithood, patriarchs of Orzhova shed both flesh and emotion. This earthly slag is collected and formed into thrulls. A single Thrull also appears in Dissension under the Rakdos Cult.
Though executed centuries beforehand for his creation of the Derelor, Endrek Sahr found himself free once more thanks to the erratic fluctuations of the time streams during Time Spiral. Judging from the abilities of his card however, it seems that Sahr once more met his end thanks to his creations.
Treefolk
Sentient trees that live for centuries in Dominaria's forests. They are often seen as the protectors and guardians of their homes. There seems to be a type for treefolk for every form of tree that might possibly exist, from mighty Redwood to Rowan.
Vedalken
Of the creatures brought to Mirrodin by Memnarch, the Vedalken have evolved more than any other. Blue-aligned creatures, they are devoted to knowledge and controlling things. The Neurok people who live along the shore of the Quicksilver Sea are blatantly controlled and oppressed by the Vedalken from Lumengrid, which is composed of colossal solidified quicksilver spires, and home to the Vedalken society. The Vedalken have direct contact with Memnarch and believe him to be a god.
The Veldalken have a weird body structure. Due to their amphibian-like vulnerability, they were forced to wear power suits that covered their entire bodies in water. They also possess a second pair of arms similar to the Orochi-bito of Kamigawa. These physical features were the result from the regular consumption of Serum and evolution over many years.
Like most cards from the Mirrodin block expansions, Vedalken deal almost exclusively with Artifacts.
The set Ravnica has revealed that the race also thrived in the entirely urbanised plane. As all organic life on Mirrodin was taken from various planes, it is safe to assume that the vedalken, as well as the loxodon originated on Ravnica. Unlike their Mirrodin cousins, Ravnican Vedalken didn't need the protection of power suits and have only one pair of arms. They are, however, still mainly politicians or scholars, mainly of the Azorius Senate, and according to the books (as well as a few cards), scientists for the Simic Combine.
In one such case, a Vedalken of Ravnica has become mutated by the research of the Simic Combine, giving it the two extra arms and the gills of its Mirrodin counterparts.
Viashino
Lizard-Folk native to the deserts of Jamuraa and Shiv, the Viashino are descendants of the dragons. Quick, agile, and skilled with metalworking they rule the sands. They are constantly skirmishing with the Goblins also native to Shiv, the Ghitu tribe of humans, and even the great Shivan Dragons themselves. They live in clan communities, each led by a bey.
Viashino are also known to live within the city-plane Ravnica, in which most are members of the Gruul Clans or the Cult of Rakdos (and, on very rare occasion, the Boros Legion).
An interesting fact about the Viashino presented in the book "The Prodigal Sorcerer" is that until adulthood, their gender cannot be determined (even by themselves.) Young Viashino choose to be called "he" or "she" according to personal preference.
The Viashino haven't seen too much play in tournaments due to the availability of faster goblins and similar creatures. Viashino Sandstalker was a component of the mono-red burn decks that were somewhat prevalent in Mirage-Visions-Weatherlight tournaments.
Weird
Introduced in Guildpact, the weirds are creatures created by the Izzet League. They resembled blobs and bubbles molded together in a humanoid form. According to Mark Rosewater, a weird is a crossbreed of elementals. For example, mud elemental and an electricity elemental will result in a weird. Though there are only Four weirds so far, Gelectrode, Steamcore Weird, Blistercoil Weird and Frostburn Wierd.
In the Guildpact book, they are described as a mixture of flame, ice and wind elementals that can freely change its structure enabling them to receive attacks without taking damage (becoming misty so the weapon goes through them) and then retaliating by turning an arm or leg frosty or fiery.
Wurm
Gigantic, limbless, ground-dwelling green-mana creatures (exceptions do occur, most commonly with white mana), Wurms are related to dragons. According to legend, the ancestors of the wurm rebelled against their fellow dragons. After losing, they were thrown to the ground, beaten and stripped of their wings. They generally dwell in forests, convenient for satisfying their mammoth appetites.
However, Wurms are also found in the urban Ravnica, but usually under abnormal circumstances. The Selesnya Conclave use specially tamed and trained Wurms for offensive maneuvers. The Golgari carnomancers are sometimes hired by the Orzhov to call forth the Wurms from the underground. It would appear that the Gruul Clans have a close association to the Wurms.