Hunger of Hadar

You open a gateway to the Far Realm, a region infested with unspeakable horrors. A 20-foot-radius Sphere [Area of Effect] of Darkness appears, centered on a point within range and lasting for the duration. The Sphere [Area of Effect] is Difficult Terrain, and it is filled with strange whispers and slurping noises, which can be heard up to 30 feet away. No light, magical or otherwise, can illuminate the area, and creatures fully within it have the Blinded condition.

Any creature that starts its turn in the area takes 2d6 Cold damage. Any creature that ends its turn there must succeed on a Dexterity saving throw or take 2d6 Acid damage from otherworldly tentacles.