Chains erupt from a point on the ground you can see within range. The chains cover the ground in a 20-foot radius centered on that point. For the duration, the chains turn the ground in the area into difficult terrain.    When a creature enters the spell’s area for the first time on a turn or starts its turn there, that creature must succeed on a Strength saving throw or be restrained by the chains until the spell ends. A creature restrained by the chains can use its action to make a Dexterity saving throw. On a success, it wriggles free of the chains.    Until the spell ends, you can use a bonus action on each of your subsequent turns to tighten the chains around one creature restrained by the chains. The target must succeed on a Strength saving throw or take 2d6 radiant damage and be knocked prone.