Mervyn has four types of magic and eight increasingly potent and power-consuming spells for each: Offensive spells serve as projectile weaponry, defensive spells reduce damage etc., effect spells activate special abilities or act as area-effect attacks, power spells fuel the other kinds.
The game is set in a dungeon split into eight levels that are freely traversable (but not necessarily immediately survivable), each of which is split into a labyrinthine network of rooms and houses some benevolent glyphs, 12 hostile wizards, hordes of monsters and monster generators.