Creature class

Spellcasters come in a wide variety of disciplines. Herein is a (not complete) list thereof.

Clerics

Clerics power their spells with their faith.

Druids

Masters of the land, Druids are in direct contact with the power of the land around them.

Enchantresses

...

Planeswalkers

Incredibly powerful, nearly immortal beings, and the most powerful of spellcasters.

Shamans

A Shaman is a spellcaster whose magic is centered in emotion, ritual, and lore.

Yamabushi

Warrior shamans of Kamigawa. Notable yamabushi include: Ryusaki Kumano.

Spellshapers

...

Wizards

Wizards, or Mages, are spellcasters whose magic requires long study of books and tomes to master.

Biomancers

Genetic biologists affiliated with the Simic Combine, Biomancers are responsible for the mutants of Ravnica in their attempts to improve the life forms of that plane.

Chronarchs

Chronarchs are mages who specialize in the manipulation of time. These specialized mages are employed by the Izzet League.

Dementia Casters

Dementia Casters are members of the Cabal. They have have the unique ability to summon nightmares from his or her personal "dementia space", a place populated with the caster's greatest fears and all beings he or she has killed. Notable Dementia Casters include: Chainer, and Braids.

Elementalists

Wizards focusing on the art of controling elementals.

Embermages

Embermages are red-alligned wizards specializing in fire magic.

Enchanters

...also called Auramancers...

Lawmages

A specialized mage under the employ of the Azorius Senate.

Necromancers

Mages specializing in death magic, including the creation of undead. On Ravnica House Dimir, the secret guild, and the Golgari Swarm are known for utilizing necromancers. Notable necromancers include: Lim-Dûl, Svogthir, and Jarad.

Taskmages

Mercenary spellcasters with an arsenel of destructive spells.