Crimson Tide

You unleash a sweeping tide of blood along the ground, transforming the terrain into difficult terrain for all creatures but yourself until the start of your next turn. Creatures in the area when you cast the spell must make a Dexterity saving throw. On failure, they take 6d6 necrotic damage, or half as much on a success.

At the start of your next turn, the tide recedes as the spell ends, collecting the blood and returning it to you, restoring the 10 hit points used to cast the spell.