Curse of the Abyss

You choose a creature and throw their mind into the crushing abyss. That creature must succeed on a wisdom saving throw or be cursed for the duration of the spell.

While cursed, the creature's vision is reduced (disadvantage on all perception checks) and its movement speed is reduced by 10 feet. When you cast the spell and as a bonus action on future rounds, you may apply the sea's pressure to their body. The creature must make a wisdom saving throw, on a failure: take cold damage equal to 3d6 + (your spellcasting modifier) * (# of rounds the creature has been cursed) or half as much on a success.

A remove curse spell ends this effect

 At Higher Levels: If you cast this spell with a 4th level spell slot, its damage increases to 4d6+ (mod)*(2*# rounds), halves the creature's movement speed, and limits their vision to 10 feet as if they are surrounded in dark water. If you cast this spell with a 5th level spell slot, it increases the damage to 5d6+(mod)*(3*# rounds), the creature becomes restrained, and blinded.