The Perfect Tomb

The component needed to cast this spell is an abjurative seal of the creators own design which is tuned or linked in some inherent way to the plane of earth. The seal is meant to incapacitate and keep the target of this spell within the endless rock of the plane of earth until broken. Once a seal has been successfully used to entomb a creature, it cannot be used again to cast this spell.

With seal in hand, you attempt to send one creature that you can see within range to the endless Planes of Earth. The target must succeed on a charisma saving throw or begin to be banished.

Each round that the creature is under the effect of the Perfect Tomb, effects will stack until either the spell is completed or concentration is broken (in which all effects are removed):

Round 1,2: The target of the spell becomes restrained as earth emerges from nearby surfaces to entangle the target, slowly forming some kind of encasement of the casters choosing. If no nearby stone is available, rock will apparate from the seal itself to claim its target.
Round 3: The target is incapacitated as the earth magically locks around their appendages.
Round 4: The target is petrified as they are beginning to be transported to the plane of earth, becoming entirely entombed within its stone.

After all required rounds of concentration are completed, the target is banished indefinitely to the plane of earth. The stone around the target shines magically and vanishes, leaving only the tablet with the caster.

The seal upon the stone tablet used in casting this spell will lock into place and glow vibrantly. The seal is only removable upon first deciphering its formulae, then casting dispel magic at the appropriate level.

When this spell is cast at each level higher than 5th, the amount of rounds needed to concentrate is reduced by 1. 6th (3 rounds), 7th (2 rounds), 8th (1 round), 9th (instantaneous).