Would you like to play as a Necromancer with the ability to upgrade Vampires?

Vampires? (They can take 15 at max consumption without losses)

Why not max consumption? :D They can only take max consumption with the support of 200-300 skeletons or a similarly strong army, or at worst, with mass slow, or with good stats and skills, etc.

Added 2 minutes later

And the standard increase for Necropolis is always the same.

12 vampires maximum. And there are different types of "nychki" (hidden units) ;)