Red is the hyperactive little brother of blue. It likes to just rush right into things and be as aggressive as possible. It rules over the elements of earth and fire, along with anything else that may become mountain-related. This eventually resulted in being able to use ice, since mountains tend to be very cold locations. It does share electricity with its blue rival, however. Sometimes, it doesn't even know what it's doing itself, and introduces random effects into the game. Red is based around impulse, fury and destroying things. Red is a great color for players who like to play fast, aggresive and keep their oppenents on their toes. It is very hard to cope against Red because you get no time to think. Spells that would sum up red: Lightning Bolt, Pillage, Wheel of Fortune, Flametongue Kavu.
In the old days, red was actually a slow color. There was more emphasis on a controlling/burn element leading up to gigantic red dragons. It was slow to really develop its own playable identity other than providing combo pieces. With the advent of Sligh, though, red surged into becoming the most aggressive color, emphasizing cheap power with brittle toughness. Red eventually became the "tricky" color, including the ability to change spell targets and temporarily gain control of creatures.
Nowadays, red can easily go in several directions. The most well-known method would be aggressive creatures with direct burn spells to kill anything that gets in their way (or just supplement the damage from creatures). Because it contains many means of directly damaging the opponent, it also works very well in combos to repeatedly deal damage or deal obscenely huge amounts of it. One of the most annoying, albeit highly effective aspects is land destruction, depriving the opponent of any mana sources and effectively locking him out of the game.
Red Creatures are very aggressive but not too bright. No creatures prove this better than Goblins. They're small but fearless, and there are tons of them. Giants, Orcs, and Ogres are some other types of red Creatures. They're bigger and meaner than Goblins but just as stupid.
Dragons are the exception among the red creatures. Dragons are huge, smart and cruel. Goblins are their popcorn. Clever red mages have both on their side.
Unique to red
Direct damage to any target - Incinerate
Temporary control - Threaten
Sweeping damage - Pyroclasm
Power enhancing - (create)
Cannot block - Stun
Ping - Prodigal Pyromancer
Mana flaring - Desperate Ritual
First Strike - (create)
Forking - Shunt
Land Destruction - Stone Rain
Artifact Destruction - Shatter