Oreads with this racial trait mimic the healing abilities of the mephits, gaining fast healing 2 for 1 round anytime they are subject to acid damage (the acid damage does not need to overcome the oread's resistances or immunities to activate this ability). The oread can heal up to 2 hit points per level per day with this ability, after which it ceases to function. This racial trait replaces earth affinity.
