Elovan's Anvil Underwear

You attempt to create an anvil around the waist of another creature. They roll a dex save to avoid the spell on a failure a large heavy anvil molds around their wait and weighs them down. The anvil is considered worn and spells that teleport also teleports the anvil with them. After being affected, creatures have half movement if their str is 15 or greater and quarter speed if less than 15 and are considered immobile if their str is 10 or less. It is considered light armor for the purpose of doffing but you gain no armor bonus from it.