Illusionist

An Illusionist is a form of Specialist Wizard in Dungeons & Dragons. Practicing the school of Illusion, the magic of altering perceptions and playing upon the mind (which, alongside Enchantment, is one of the schools that most overlaps with psionics), Illusionists are actually the oldest specialist caster in the game - introduced way back in ADvanced Dungeons & Dragons 1st edition, they were an entirely separate class to the original Magic User. This early proto-class traded access to the Magic-User's spell list and to most of the magic items in the game to instead wield its own spell-list full of mind-whammying spells, which were gimmicky but powerful if used right. From this basic concept, the other specialist mages of AD&D 2nd edition were born.

Like Enchantment, Illusion suffers heavily in 3rd edition because practically every other monster in the game is immune to it. They also suffer a stigmata of being heavily associated with gnomes; it was literally the only kind of wizard they could be.

Illusion is, in many ways, one of the most "grounded" magical styles, with a strong history in pulpy fantasy stories like Conan the Barbarian.

4e Illusionist

The Illusionist returned as a subclass for the Mage in Dungeons & Dragons 4th Edition. Being an Illusionist was handled as a set of three features gained by choosing that specific magical school, and which were acquired at levels 1, 5 and 10. A Mage could also dabble in Illusion by taking the 1st and 5th level Illusion school benefits at levels 4 and 8.

• Illusion Apprentice: When you hit a target with an arcane illusion power, the target takes a -2 penalty to the next attack roll it makes against you before the end of your next turn.
• Illusion Expert: You gain a +2 bonus to Bluff checks and Stealth checks.
• Illusion Master: When you hit or miss a target using an arcane illusion power, the target grants combat advantage for the next attack made against it before the end of your next turn.

5th Edition's Arcane Tradition

Illusionists are simple but effective, focusing on super-charging their illusions in various ways. At level 2, thanks to Improved Minor Illusion, not only do they get the Minor Illusion cantrip for free (or a bonus cantrip, if they already knew it), but now they can make both sounds and images in one casting of Minor Illusion. Their level 6 feature, Malleable Illusions, lets them reshape their illusion effects on the fly. Illusory Self, their 10th level feature, gives them the power to force an auto-miss on an enemy attacker once per day by using a reaction to make a one-shot illusory double take the hit for them. Finally, their most potent ability is the level 14 trait of Illusory Reality, which lets them make aspects of their illusions real for a short time. Say, making an illusion of a bridge over a chasm that you and your buddies can run away over, but which will drop anyone else straight through it, Looney Tunes style. Some DMs may actually agree to interpret this ways that're even more powerful, such as using it to create expensive spell components or to defeat enemies by encasing their weapons (or bodies!) in blocks of "faux-real" stone.