Malistaire vs Morganthe. She'll win just because she's mean. He's really a big teddy bear. Look at all the trouble he went through to bring his wife back :D
The Onis War Oni, Plague Oni, Death Oni, and Jade Oni
VERSUS...
Leaders of the Coven Mord RuneChanter, Othin StormFather, Munin MistWeaver, and Kol ShadowSong.
Honestly, the Raven Leaders of the Coven. Those guys will DESTROY you if you go in alone. As for the Onis... my friend soloed the Jade Oni at level 32 and beat him at the first try.