Vivi's Doomsday

In order to get Vivi's ability doomsday, you need to obtain the "Mace of Zeus". you can find it in the memoria, on the terrace displayed above the "burning planet" screen. when you get to the screen that shows the "burning planet" go up the ladder and proceed to the upper level. it is sitting on the left side of the pink ledge. examine the area with the "x" button.