Speak to Head Scholar Nabihan at 4426, -821, 360 in Cobalt Scar to begin this quest.
A good spot for a barrel!
Pick up four barrels in the tent at 4426, -823, 491 .
Head southwest to the Drakelands.
Place and blow up the barrels near the water (two clicks). Run away before it explodes and you can either kill or keep clear of the patrol that is drawn to the sound.
NOTE: If you fly away fast, there's a chance you'll go too far and the explosion won't update the quest. If this happens, you'll have to delete the quest and start over - there are only four update locations that disappear and don't respawn. Known locations:
5026, -1089, 1092
4994, -1080, 1354
5121, -1091, 1596
5256, -1079, 1016
Return to Head Scholar Nabihan to complete the quest.
Field Marshal Vishra will now offer his final quest, Tear in the Grotto.