Yup, anything that finds a way to bypass his toughness("Poison" like you find on the Plaguebearers, Rending weapons, Snipers, or high strength weapons) are gonna do the trick.
There's one weapon in the chaos arsenal that you must not forget when you're talking about things that could bring a c-tan down quickly and surprisingly.
It belongs to the Deathguard traitor legion of Nurgle and it is the Plague Sword. It is a paltry 25 points to field but you may give it to as many aspiring champions, sorcerer lords, and chaos lords as you have in your army to the opposition's dismay. Anyone who has access to the chaos armory and has the mark of nurgle may wield it.
What it does it...
Roll to hit and would as normal. If a wound is caused and the armor save or invulnerable save isn't made, then the nurgle player rolls an additional d6 and on a 4+ the model is killed instantly regardless of wounds.
This gives the nightbringe, the Deciever or any monstrous creature with more than 1 wound something to worry about. It goes beyond the plague knives of the plague bearers.
If what I say makes you queezy, don't worry. With a chaos space marine from nurgle having a max strenth of 5, they'll need 6s to wound so it's not very likely. Demon Prince is a different story. But, if the hits from the plague sword keep coming, that necrodermis is going to give way in a big way.
