Thoughts on porting Summon Undead to Pathfinder

[Slayer Lord]

Exactly what it says on the tin. I've always really liked the idea of this spell, but it's so horribly unbalanced. I've found some ideas elsewhere online, but I wanted to get the Playground's take on it too.

[Zanos]

What's wrong with it?

[Coidzor]

What's so unbalanced about a summoned skeleton, zombie, or even ghoul?

Shadows and Allips are pretty potent, but ultimately their ability to target ability scores isn't going to break the game unless the GM really wants big stupid creatures with no magical support to feature prominently, but there are plenty of other spells that ruin those things' days anyway.

You can already set off a Wightocalypse just by using Enervate or giving a creature too many unholy/holy/anarchic/axiomatic arrows.