Human's Explosion Stone

The next task is a huge one. You will have to pay more attention for this one than any of the other tasks I assigned you. If you go east of the Ten year Desert, Mastcot appears, and in the air you'll see a huge ship. We call that Terranoa, and it was a major culprit in the downfall of my Empire! All the tasks I've asked you to do were leading up to taking my vengeance against them. Let me tell you how I'll do that. You still have two more things to do for me. If you look in the western part of Membreathen, the land of Humans, you'll find the Warrior's Bridge. Buried under the Milestone is the Explosion Stone. It's there to instantly block intruding enemies by blowing up the bridge when they need to get into a defensive position. I need that Explosion Stone. Bring it to me.

Oh, you have to keep your promise. Bring the Explosion Stone from the Milestone at the Warrior's Bridge located west of Membreathen.

Good job. It won't be long before I achieve my dream!