Domain Expansion: Hypoxia Pool of Suffocation

You create a 30-foot-radius, 30-foot-tall cylinder of energy barrier centered on a point on the ground that you can see within range. Anoxic sea water, fresh water, or groundwater that are depleted of dissolved oxygen erupts from the center and filled the cylindrical domain to the brim. The water swirls around the target within the domain, forcing itself into the creature’s mouth and nose, subsequently filling the creature's lungs with the anoxic waters and setting in the conditions of hypoxia. Due to the anoxic properties of the waters, prolonged exposure will ultimately lead to toxic shock and possibly death.

The target must make a constitution save or begin coughing and hacking to expel the water from its lungs. On a failed save, the creature is considered incapacitated for 1 round and takes 4d4 necrotic damage at the end of each of its turns. The creature may make an additional Constitution save at the beginning of each of its turns. On a successful save, the spell will end allowing the creature to breathe again. This spell has no effect on creatures that do not breathe.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the creature is incapacitated for 1 additional round.