STOP SAYING TZEENTCH TERMINATORS!!! Nothing gets a save vs. The Nightbringer...of ANY kind.
That being said. I tested abaddon vs the nightbringer a few times. It's a toss up. With good rolls Abbadon can put the hurt on TNB, but i've had a few times where TNB has gotten the charge, lived, and wiped Abbaddon out in one swipe.
Also, to whoever said it, since they're both independent characters, and both in base contact, TNB can choose to engage only abaddon, thus the wounds go to him.
Though for 90-ish points less than TNB, he puts up a good fight.
Abaddon + 2 chaos termies w/ powerfists seems to be the logical choice. This presents a choice for the mighty nightbringer. TNB can try to kill everything indiscriminately, which lets the Abaddon live a little longer, or just attack abaddon, which allows for 4-6 power fist attacks (depending on who gets the charge) on top of abaddon.
Correct me if I've misread the rules.
Originally Posted by Wolf_Lord_Skoll
Nids have it easy. 2 fexs talons, toxin sacs, bonded exoskelton, toxic miasma and reinforced chintin. Throw them both into combat and laugh. Even the nightbringer will have some trouble with that, he only has 4 attacks meaning he cant kill one outright.
TNB has 5 attacks, 6 on the charge, so yes, he can kill one outright, but with 4's to wound it's not very likely.