Khorne Daemons are hard to ignore. Bloodletters are ungodly for only 7 points.
A unit of 30 can:
1) Deepstrike
2) Charge
3d6 inches, re-rolling if a character is nearby and getting +1 if they take an instrument (which they should)
3) hit on 2+ with 61,
str 5, -3ap 2dmg on a 6+ wound roll
4) do it all again for 3
cp
Apart from the
cp cost (which can be made up for with a cheap battalion of brimstones or nurglings) I can't see anything else comparing.
Plus khorne daemon princes are brutal, if they take claws they're getting 8
str 8 -2ap 2
dmg attacks. If they take skullreaver they'll do around 20 wounds to a knight each turn of combat (again fighting twice of the have the
CP).
Pair that up with some chaff clearing from pink horrors, and some psychic support from thousand sons and you're all gravy