The leader is Niv-Mizzet, the Firemind.
the champion is Melek Izzet Paragon
The planeswalker of dragons maze also belongs to this guild
The Izzet League are a group of mad scientists.
The Izzet are mad scientist-wizards, who experiment with all kind of weirdness, and then jump to another subject to study it. This may sound too weird to you to form a nice deck, but the fact is that the deck can work out pretty good. It isn't all that mad (if you do not count the newly created creature type "weird"), and it's always fun to play with the Izzet. The mechanic in this guild is Replicate, which lets you copy the spell you are playing as many times as you can afford with your mana. For example, the card Pyromatics costs 2 mana and deals 1 damage to target creature or player. If you spend 10 mana, you can deal total 5 damage to your opponent and/or his or her creature(s). The effects of your cards include dealing damage as in the example, tapping (Gigadrowse) and returning creatures to owner's hand (Vacuumelt), and even putting "3/3 blue Weird creature tokens with defender and flying" into play (Thunderheads).
Various creatures will gain benefits from you playing bunches of spells, such as Gelectrode, Wee Dragonauts and the legendary Tibor and Lumia. The useful Izzet Chronach will let you play your best card again.