If he's in the Elven Halls, you could wait until you get rElec, then go into Elf:3 solo and lure Nikola down where the treasure loot is. Then as all the Deep Elf Sorcerers/High Priests/Demonologists/Blade Masters/Master Archers are swarming out, turn Invisible. Nikola will fire off Chain Lightnings in attempts to hit you, and in the process he'll be obliterating all those freakishly powerful elves as well, providing you with powerful covering fire on accident.
It is a risky gambit but definitely viable. If Nikola was on Elf:3 in one of my games, I'd definitely try it. But not without the Elf:3 equipment/spell essentials, of course, and not without rElec, because Nikola's Chain Lightning spell can literally kill you in one turn with it if he ever gets to cast it while adjacent to you and you can't resist it, burning through hundreds of HP instantaneously. There's not a lot more magnificent and beautiful ways to go than to be vaporized by an electric death ray, I'll admit, but since the idea is to not die at all... mmmyyeeaaahhh...
Edit: Nikola's not an elf, but since you are an orc, it's understandable and in fact encouraged to call anything you hate an elf. And
boy howdy that Nikola can be one son-of-an-elf-bastard.