Soulless¶

Soulless creatures do not have a soul, and are generally those who are created by another creature, such as many Construct creatures, Undead creatures, and war dogs. There are a few abilities or other rules in the game that can only affect creatures with souls. Soulless creatures are immune to these effects. Likewise, if a rule only affects a creature without a soul, soulless creatures are the only valid targets for such effects.

Source: Draw Steel: Monsters · printing 1.01