Foxdemon, it's pretty rare, so I understand. My last few worlds I got one to drop fairly quickly, but that's just luck I think. I've read how people set up crimson knight spawners/grinders by walling the clerics in while invisible so they can't aggro, then just killing the knights in endless waves until the darn thing drops.
Necromancy, hm? Gravestone altars that can resurrect bodies.
INTERESTING
I just happen to have saved the bodies of a few villagers of interest, who had good trades before they died. It would be awesome if I could resurrect them. The villagers you create via the Vat are always random...no telling what sort you'll get, or what trades they'll have.