Greater Entomb

5-level Necromancy

You choose a creature within range to construct a tomb of necrotic energy around, keeping them trapped inside its walls. The target must make a Strength saving throw. On a failure, it is locked within and pierced with a thousand spikes, and magically dealt 5d12 piercing damage. The target makes the saving throw at the end of each of its turns, taking the same damage on a failure. On any success, the tomb shakers apart and fades away, freeing the target. The creature has total cover while the tomb lasts and can’t move or escape by any means other than teleporting.   An undead target has disadvantage on its first saving throw against this spell.   A creature that fails every save against this spell or is reduced to 0 hitpoints while inside is locked within. The duration becomes permanent. A dispel magic spell can end the spell only if it is cast at 5th level or higher on the tomb. The tomb has 50 hitpoints, 15 AC, immunity to poison and psychic damage, and resistance to all other types of damage except force.
At higher levels: When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d12 for each slot level above 5th