Chains of Kar'Kradas

The target must make a Dexterity saving throw or be wrapped in chains forged of pure darkness pinning them to the ground. When pinned like this they are grappled and  restrained. When restrained this way on each turn after the target can make a Strength saving throw to break the chains. If they fail they take 2d10 Cold Damage. 

For each level above 3rd the damage increases by [roll]1d10[/roll].