Undead are former living creatures now sustained by void energy and unholy magic, rather than biology.

At 0 HP they are normally destroyed instead of falling unconscious, unless a specific ancestry or rule (such as Corpsefolk/Borai PC options) overrides this.

They are damaged by vitality energy, healed by void energy, and don’t benefit from vitality-based healing effects (standard “healing spells” for the living).

Trait package (typical): darkvision; almost always unholy; immunities to death effects, disease, paralysis, poison, and sleep or unconsciousness (plus mental immunity if they’re mindless).

In Starfall terms, “Undead” is a core creature trait you add to stat blocks to signal void-powered physiology, nonstandard healing, and the “destroyed at 0 HP” endpoint that makes them feel more like hostile phenomena than durable citizens.