Disintegrate

The damage dealt increases to 3d6 points of damage per caster level (maximum 60d6) plus 1d4 points of Constitution damage. A creature that succeeds at its saving throw takes 5d8 points of damage plus 1 point of Constitution damage.

A creature whose Constitution score is reduced to 0 by this spell is entirely disintegrated.

Augmented (7th): If you expend two uses of mythic power, you fire two rays.

Alternatively, you may fire only one ray, but if the target is a non-mythic creature and it fails its saving throw, it's automatically disintegrated regardless of its current hp.