Entomb

You choose a creature within range to magically construct a coffin around, shutting them within with overlaying chains. The target must make a Constitution saving throw. On a failure, it is locked inside, stabbed with a hundred blades, and magically dealt 5d12 piercing damage. The coffin turns to ash at the start of the creature's next turn. The creature has total cover while it lasts and can't move or escape by any means other than teleporting. On a success, the creature takes half as much damage and the coffin immediately fades. An undead that has advantage on saving throws against or is immune to effects that turn undead has disadvantage on its saving throw against this spell. At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d12 for each slot level above 3rd.