Chains of Tharizdun

Chains of force lash out grabbing the arms of the target. The target must make a STR saving throw or become restrained by the chains for the duration. A creature may use its action to make a STR saving throw to try and break from the chains taking 2d6 force damage on a failure or breaking free of the chains on a success. 

At Higher Levels. When you cast this spell using a spell slot of 3 level or higher, the damage increase by 1d6 for each level above 2