Some ideas, though I think all our scrolls need a rewrite as they were written for a game that had 6+ modified MWs and different coherency rules and much less power level.
Blood tithe should be based on models slain (skulls collected) 8 models = 1 bloodtithe. More for heroes / generals etc
No respite army wide ability, do not remove casualties from units until the start of the battleshock phase
Bloodreavers should have +2" range if they charge
Bloodthirsters/bloodletters should hit on 2+ since they should are the epitome of martial skill, MW on 6 to wound