The void trait marks effects that heal undead or void‑healing creatures with void energy, deal void damage to living creatures, or otherwise manipulate void energy. 

Void is a source of energy, not a synonym for “heal undead.” A void effect might deal void damage to living targets, heal undead or creatures with the void healing ability, or simply manipulate void energy in some other way, but it only does what its text says. Creatures with void healing don’t take void damage and are healed by void effects that specifically say they heal undead, while they are damaged by vitality damage and do not benefit from vitality healing effects.

• Living creatures can be harmed by void damage but cannot be healed by void healing.

• Undead / void‑healing creatures are healed by void healing, are immune to void damage, are damaged by vitality damage, and don’t benefit from vitality healing effects.

Planes and regions with the void trait are hostile to the living: they are vast, empty reaches that strip life away, inflicting void environmental damage on living creatures each round. In the strongest parts of such a plane, this void damage has the death trait; if a living creature is reduced to 0 HP and killed by this damage, it crumbles into ash and can rise as a wraith.

As with vitality, key spells and abilities are explicit exceptions. Touch of the Void heals a willing undead creature or deals void damage to a living creature with a basic Fortitude save, while Execute flips between void and vitality based on whether the target is undead or has void healing. Feats like Nudge the Scales let you choose to gain void healing for a day, effectively moving yourself onto the “void side” of the healing axis.