Fiendmasters is good provided you are not using a set with a chest piece. That is kind of its only real downside imo. I do use it on my Pet Deceiver Scheherazade - Pet Deceiver
As for Necrolord’s, personally I only really use it in Lost Souls builds or if I need to desperately get Familiars to 26/16 and there is no other option. I wouldn’t be against buffing it.