A sphere of crushing water forms around the head (or similar) of a creature you can see within range, and begins to exert an incredible force upon that creature. When you first cast this spell, the creature affected by it takes 6d10 bludgeoning damage. As a bonus action on any of your turns for the spell's duration, you may cause the creature to take this damage again. A creature under the effect of this spell is considered to be holding its breath (and eventually suffocating) as described under the rules for suffocating on page 189 of the Player's Handbook, unless the creature is able to breathe water. On its turn, a creature under the effects of this spell may attempt to pull itself from the sphere as an action. If it does so, it must succeed on a Dexterity saving throw against your spell save DC or remain stuck in the sphere. Once a creature removes itself from the sphere, the spell ends.