1. No summoning of zombies by anyone including the necro.
2. No killing out of pk range pets.
3. Capping what you can raise to what you killed. Use similar mechanics to gank code. That way a hero can't get you a pile of corpses. OR make raise dead dependent on the level of the corpse. So the lvl 30 will struggle to raise a lvl 50+ corpse just as it would to land a spell on them if the mob was living but on the off chance might get one.
The vision here would be to make zombies closer to the level of the pk range and keep the combat to the pk range. That way if victim can make the necro run the necro might as well raise a new army cause he was bested.