Eternity of torture

The subject's body is twisted and warped, wracked forever with excruciating pain.
The subject is rendered helpless, but—as long as the spell continues—it is sustained and has no need for food, drink, or air.
The subject does not age—all the better to ensure a true eternity of unimaginable torture.
The subject takes 1 point of drain to each ability score each day until all scores are reduced to 1.
The subject cannot heal or regenerate.
Lastly, the subject is completely unaware of its surroundings, insensate to anything but the excruciating pain.
However, even if the saving throw is successful, the target still feels terrible (but temporary) pain.
The target takes 15d6 points of necrotic damage immediately and takes a -4 circumstance penalty on attack rolls, saving throws, skill checks, and ability checks for 1 round per level of the caster.