Breaking The Chains
The water weird are a life form originating from the elemental plane of water. The can hide within water even in front of a being. A detect magic will reveal that the water they reside in is indeed magical. They attack all living thing, feeding from their essences in some unknown matter.
The creature forms in but 1/2 an action appearing as a serpent and lashes out at a nearby opponent. They are immune to slashing, piercing and bludgeoning weapons but appear to be vulnerable to fire.