I read Felos's book. It's the sickest and most bizarre book I've ever read.
That 'draining energy from the dead' aspect you mentioned is significant to me. It is clearly, in occult terms, one of the more evil forms of necromancy. Simply seeking out spirits of the dead to talk with them is bad enough. To attempt to feed off their souls, that's in the realm of sick 'Elric' perfidity.
In pyschological terms, it is evidence of someone who could easilly be capable of cold-blooded murder.
People might call it overkill. I like overkill.
FReegards...