Blood Pudding

You fill a 20-foot radius sphere with blood in a pudding-like form. Living creatures must make a Constitution saving throw or take 3d8 necrotic damage and are suffocating. On a success, they take half-damage and are considered to be holding their breath. Creatures who start their turn inside the sphere take 1d8 necrotic damage at the start of their turns and if they passed the initial save must repeat the constitution saving throw at the beginning of their turns or be considered suffocating. The area is heavily obscured and considered extra difficult terrain unless the creatures have a swim speed, in which case it is just difficult terrain.

Creatures who are suffocating are unable to speak to cast the verbal components of a spell.