Aura
Unless an aura says otherwise, a target is affected by an aura automatically with no action required on the creature’s part, whenever the target is within the aura’s listed range (either when the target enters the aura on its turn or when it begins its turn in the aura, whichever comes first). If the aura deals damage, it damages a target only the first time the target is in the aura each round, regardless of how many times within the round the target enters and leaves the aura. A creature can suppress its aura for 1 round as a move action unless noted otherwise.
Format: Aura radiation (30 ft., Fortitude DC 17); if additional information is needed, the aura also has an entry in Special Abilities.
Source
Alien Archive pg. 152
