Remek the Necromancer
The protagonist Drake Dragonmuster and his companions face Remek in his first form in the Seventh Hell, where he confronts them as they try to steal the source of his power. He is a powerful mage in battle, and can summon undead. He can be killed by either Geldan the Red using Red Inferno or by Sophia using Mystic Tempest, both high-level spells.
Remek in true form
After Remek is defeated, Drake Dragonmuster and his companions continue to destroy the source of power. After they do, Remek returns in his true form: a huge turtle-like demon that is powerful in both attack and magic. Remek is one of the game's toughest foes, but can be beaten. After Remek is defeated entirely, the heroes believe that Jadea is saved, until Lucifarron Master of Hell surfaces, as the true antagonist.