The most useful of all is the Vampire! I consider him the main counter to Water Elementals and Djinns, but if you cast antimagic on him, everything is fine. Plus, give him dragon strength, and most importantly, give him cat reflexes, which allows him to attack twice without retaliation and drain life twice! :) It's a pity you can't cast blessing on him. :(
Without casting these spells, I could kill creatures of the highest levels with Vampires (including the Dragon King), of course, there were more Vampires, but they are 3rd-level creatures, so there should be more of them.
And in general, a great unit, capable of doing what others cannot:cool:.