trentonjoe
Explorer
Yes, he will need the proper supporting monsters to make his entrepreneurial venture in fine dining a success. The more I think about it, the more inclined I am to write an adventure around this guy. If I do, I'll share it here.
I was really intrigued about this guy as well. I think the spell like ability mechanic is a little quirky but I love the idea of giving him spell levels (4,5 and 6) without any spells for those slots.
I would suggest just saying they cast spells as a 13th level wizard but only know 2 spells from levels 1-3 and Finger of Death.
A cabal of these things who loosely work together but each have their own lair and territory spread out over 100 square miles or so would be super cool. Each of them could have different spells and minions. The ghouls and finger of death would be constant but allowing spell choice would give each an "identity".
I also think they would avoid "finger of deathing" humans because the zomieifcation ruins the meat.
Just eyeballing it this guys looks like a CR 3/4 as written. If you allow the extra spell slots and choice of spells it would be more like a 5.