An interesting concept, though I think the execution itself is a little clunky. Even after reading the entire descriptive text, I think I'd need to see this in play before I really get how it would play out. Also the duration seems very short - while it has the potential to be a powerful effect, with the small radius and the high level required to use the spell, I don't see it being selected very often. Interesting flavor add-on with the special DC adjustment, though, I like that.

The following is based on Jailhouse Rock:

Stone Tomb
Transmutation [Earth]
Level: Cleric 4, Druid 4, Sor/Wiz 5
Components: V, S
Casting Time: 1 standard action
Range: Close (50ft + 5ft / 2 levels)
Target: One creature
Duration: Permanent
Saving Throw: Will negates
Spell Resistance: Yes

With a word and a simple gesture, you entomb a single creature within a nearby stone. The stone must be large enough to encompass the creature's entire body and its equipment; if no stone, or no stone body large enough, is nearby, this spell gains the conjuration (creation) school and subschool and creates a pillar of stone adjacent to the target creature, with the minimum dimensions to contain the creature.
While in the stone, the target of this spell remains in contact, however tenuous, with the face of the stone through which it melded. It remains aware of the passage of time and can cast spells on itself while entombed within the stone. Nothing that goes on outside the stone can be seen by its prisioner, but they can hear what happens around them. Minor physical damage to the stone causes no harm to its prisoner, but partial destruction (to the extent that the creature no longer fits inside) expels the creature and deals 5d6 points of damage. The stone's complete destruction expels the prisoner and slays it instantly unelss it succeeds on a DC 20 Fortitude save.
Unlike meld into stone, the target of this spell cannot voluntarily leave their stone tomb. In addition, a stone to flesh spell cast upon the stone forcefully expels the prisoner and deals 5d6 points of damage to it. Stone shape deals 3d6 points of damage but does not expel the prisoner. Transmute rock to mud forcefully expels the contained creature and slays it instantly unless it succeeds on a DC 20 Fortitude save, in which case it is merely expelled. A passwall cast upon the stone shifts the imprisoned's position within the stone outside of the location of the passwall, if the stone is large enough to accomodate this; otherwise, the prisoner is expelled and dealt 5d6 damage.

Next Challenge: EITHER something based on dubstep OR something based on a song from before 1900.