From Divinity Engine Wiki
- query CharacterIsSummon([in](CHARACTERGUID)_Character, [out](INTEGER)_Bool)
Returns whether _Character is a summon. Summons can be player-controlled or not.
- Success/Failure: Fails if _Character does not exist.
- _Bool: 1 if _Character is a summon, 0 if not.
- Summons can also be distinguished by the fact that hey have the SUMMON tag.
- If you wish to know whether a summon is player-controlled, also check CharacterIsPlayer.