yes, he'll get some purple items. The main thing is that there will be a combat skill branch, which is useful for an assassin. The usefulness of this lies in getting +3 to speed for a mage-necromancer. His job is to cast spells, not to fight. So, specifically, I consider the assassin to be a useful class for the Necropolis. At least one of the useful ones.

The problem is that assassins are more often given skills from the Warfare skill tree than from the Death Magic skill tree. And we primarily aim for a mass cancel on the first turn. Warfare is needed for a magus and for general defense. It's not always possible to develop the Death skill tree to its final stage. But even so, an assassin, fed with emeralds for speed (just in case), can deliver a very unpleasant surprise to the enemy. It is also desirable to have Devils in your army, rather than Dragons, so that you can immediately finish off the enemy tactician or the most dangerous mage - when the assassin removes their immortality.