Virulent is the head of the Dragon Clan and main antagonist of the game as well as the final boss if your character alignment is good.
Experience Given: 582183
Once you've reached the last room in the Temple of Shame, Virulent will turn himself into a dragon for a fight. He, much like Ghost of Ladon, has one quick attack, and a screen clearing mateo-esque spell. He is rather slow for his size, so keep moving around the arena, taking shots at him immediately after he uses Mateo. Watch out for spike traps in the arena. His Mateo-esque spell has a high chance of missing (especially for assasins since they run fast) if you keep moving. Keep a solid offensive and use a maxed screen clearing move of your own if you have one and he'll go down very quickly.