Tentacles of ink

long, black tentacles sprout from your hands until they are dispelled.

When a creature  enters the affected area for the first time on a turn or starts its turn there, the creature must succeed on a Dexterity saving throw or take 2d8 bludgeoning damage and be restrained by the tentacles until the spell ends. A creature that starts its turn in the area and is already restrained by the tentacles takes 4d8 necrotic damage.

A creature restrained by the tentacles can use its action to make a Dexterity check  against your spell save DC. On a success, it frees itself.