One of the most important items in the game, it allows you to obtain the Soul Fusion Monster Amon! Getting the Destruction Stone is a little annoying though. You need to have obtained all of the three chests that are seal by that mystic light in the Neamton Basement. Then go to the stone circle and wait for the ? appear over Yuri's head and the Destruction Stone will float down and Yuri will grab it. Also this item is also partly responsible for obtaining the Seraphic Radiance since you need all the fusion monsters to get the Seraphic Radiance.