Carnivorous Swarm

A terrain effect

Description from the Dor Un Avathar

Something small and annoying is eating your flesh if you enter this area, which should be marked with a red ribbon. Take a wound to any location (player’s choice) after 5 seconds and die in a 10 count. Invulnerabilities are worn through all locations at the rate of one point per second after the initial 10 seconds. Normal armor is automatically bypassed.