Undo

You and one other friendly creature who you touch while reciting the verbal portion of this spell are sent 2 hours back in time. Everything is as it was 2 hours before the spell was finished, and only the two targeted creatures remember that which is meant to happen. For the next 2 hours, any rolls made by you and the other target have advantage. All attacks made against you and the other target also have disadvantage.
If this spell is activated without performing the ritual, having the spell prepared, and using a 9th level spell slot, roll a d8. This effect also happens if you would attempt to cast this spell again before 386 years have passed. On a 1-4, the spell fails and you and your target die. Your bodies turn to ash, your soul dissipates, and you cannot be revived or recreated. On a 5-7, the spell fails and you and your target age 10d20 + 200 years instantly. If you would not die, all of your ability scores get a permanent -6. This aging cannot be reversed except by divine intervention. A creature that would die from this effect cannot be revived. On an 8, the spell fails, and you and your target are thrown into a pocket dimension. The dimension is empty space. No magic can be cast within the pocket dimension, except the Wish spell. Undo cannot be cast within the pocket dimension, even with the Wish spell. Once a creature has left the pocket dimension, they can never cast Undo again.