the nightbringer has some pretty evil abilities if you ask me, the ability to charge in over and over giving him 6 attacks can wipe out most CC even if they attack first with their initive, since in the begining of the enemy assult phase after moves have been made but before any blows are struck the nightbringer may harness its power to summon etheric winds which hurl its opponents away from it any enemy unit with a model within 6 inches (not vehicles) which has a str lower then 4 unmodded must move 2d6 inches directly away from the nightbringer. its not THAT useful (since its str 4. I think it should be STR 5 cuz of all the damn SM's around) but this does not work to break close combat with any troops (too bad)
all in all, if you wana take ou the nightbringer, use multi attacking high STR attacks. else the wounds attacks and his attacks will destroy you.