Bone maiden

when you cast this spell you summon an iron maiden made from bones the target must make a dexterity saving throw or be trapped by it. a trapped creature is restrained and blinded and takes 3d6 piercing damage at the start of each of its turns. a huge or larger creature cannot be trapped by it, the trapped creature can try to escape by destroying it it has 50 hp and 15 ac and immunity to psychic and poison damage.