Nerus is an Aleroth Champion in Divinity II: Flames of Vengeance. He is first seen during a brief encounter at the Circle of Trust Inn in Mardaneus Plaza, where he quickly recognizes the Dragon Knight and excuses himself before leaving.
Nerus is met again near the Crow's Nest waypoint shrine. When confronted, he reveals that he has acquired an ancient Maxos magic spell, and plans to flood Aleroth with legions of the Damned One's troops to take down the city from within. It is too late to prevent him from casting it, and eventually the spell takes effect. Unfortunately for Nerus, the spell falls short of an inundation of troops, with only three Black Ring members being teleported to the site. You must fight Nerus (level 40) and the three Black Ring members (level 39) simultaneously. To simplify the battle, focus on killing the healer first.