Annihilation Spectacles

Creatures viewed through these darkly tinted glasses sometimes seem, ever so briefly, to flicker in and out of existence. A transmuter can use these spectacles to spontaneously convert any prepared wizard transmutation spell into any other wizard transmutation spell he knows; the desired spell must be of the same level or lower than the prepared spell. Once per day, he may use the spectacles to spontaneously cast disintegrate in place of one of his prepared transmutation wizard spells of 6th level or higher, even if he doesn't know that spell.