When a corpselight is reduced to 0 Hit Points while merged with a corpse, it is instead reduced to 1 Hit Point as the corpse collapses to the ground and the corpselight emerges in its wisp form. A corpselight that starts its turn in wisp form must attempt a flat check at the end of its turn; if it fails, it loses 1 Hit Point. A corpselight reduced to 0 Hit Points while in wisp form is destroyed.