Entity: Pelagic Merfolk

Source Howl of the Wild pg. 36 ^2.1

You're a merfolk of the open seas. Your tail is patterned after the silvery tuna and herring that school by the million in your hunting grounds. Water obeys your will, and with a quick word, you can draw a sheathe of it around you. You gain the Shielding Wave action.

Shielding Wave (primal, water) You raise a magical barrier of twisting currents. Until the start of your next turn, the first time you take acid or fire damage, you gain resistance to that damage equal to half your level (minimum 1). The resistance is equal to your level instead if you're submerged in water, if you already Cast a Spell with the water trait, or if you used another ability with the water trait this turn.