Are Undead Exempt from being targeted by Spells ...

[Noirianna]

(Are Undead Exempt from being targeted by Spells) when the term "living target" is used in the spell description?

For example, I wanted to make a character that could negate hostile spell-casting ability. To that purpose, I picked Summon Swarm for its catch-all spell disruption via the concentration checks it forces on its targets. But when my team ran into an undead caster we found that Summoned Swarms target "living creatures". So we had to come up with other ideas at the last instant to hinder that particular bad guy during our adventure.

Any help or advice appreciated.

[Sandslice]

https://paizo.com/threads/rzs2jz5v?Living-Creature-Definition#4

Per this, "living creature" means you have non-zero Con. Undead and constructs are not living, and are thus invalid targets for spells that care about living creatures.

[willuwontu]

Magic Rules wrote:

Many spells affect “living creatures,” which means all creatures other than constructs and undead. Creatures in the spell’s area that are not of the appropriate type do not count against the creatures affected.

[AwesomenessDog]

Technically, summon swarm attacks all creatures in the area regardless of whether they are living or not, but they will only follow/chase living creatures as targets.

[Mysterious Stranger]

The spell is poorly written. It will attack all creatures within the area. If no living creatures are within it area it goes after the nearest creature.

So any creature living or otherwise that is within the initial area will be attacked. If there are no living creatures within the area it will pursue the nearest creature living or otherwise. Technically the swarm itself is composed of living creatures, therefore will never pursue anything. Obviously that is not how the spell should work so you need to make some common sense adjustment to RAW.

What I would do would change the spell to If there are no other creatures within its are ….