I don't know if it's just me, but the wording on the chosen warscroll for their rerroll wounds aura ability makes me think that once one model is slain by a chosen unit, all chosen units on the battlefield activate it.
Am I reading it wrong?
Gravespawn tzaangors buffed by spawn + beastlord Command can get pretty killy as they get two attack profiles. With rerolls to wound/hit on that Many attacks, you've gotta kill something.
Centigors, with their speed ,native +1 to hit and loads of attacks, are great targets for Blades of Putrefaction.
Not to mention benefits from the wheel, GUO bell and shaman for massive movement boost.
T1 charges galore!
You could even throw some wrathmongers to go behind bullgors!
4 big Axe + 4 horn attacks per murdercow. Those guys would delete anything they touch!
Or 5 attacks per bestigor on the charge.
You could even get full rerolls on bullgors if you stack a banner of Blood bloodsecrator along bullgors wich I'm seriously considering, as It would neuter one of the weak points of the unit.
I tant think warherds are great additions to khorne /nurgle as -2rend 3 damage is a pretty uncommon sight on those armies.