Hunger of Hadar
You open a gateway to the Far Realm, a region infested with unspeakable horrors. A 20-foot-radius Sphere of Darkness appears, centered on a point with range and lasting for the duration. The Sphere 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.
Using a Higher-Level Spell Slot. The Cold or Acid damage (your choice) increases by 1d6 for each spell slot level above 3.
Hunger of Hadar 5.5e 2024 vs. 5e 2014 edition differences
The 2024 version introduces the "Blinded" condition instead of just "blinded," clarifies the sphere as Difficult Terrain, and adds that Cold or Acid damage increases by 1d6 per spell slot above 3rd level. The 2014 version lacks these damage scaling and condition details.