During combat they will attempt to keep arcane empowerment active and summon a variety of creatures. They've also inherited various behaviors from the core ai*.
I've included an example creature with the script.
The necromancer familiars don't seem to be aggressive like other summons, so they are not used by default (optional param).
The necromancer animate dead spell attacks mobs by default, so that is off as well (optional param)
* Some of the inherited behaviors could be replaced, if you feel like it. If an enemy is low on health and they are chasing, they will follow and cast regular mage spells. I figured this was ok. They also will run away from melee combatants. If they are engaged before a target attacks a summon, it can be an easy fight, so it's probably better to spawn them with other mobiles.
There's a lot of room for improvement but as a proof of concept I think it turned out well.