Overlord Krom'gar sends word from the base. You are to get back on the Krom'gar hot air balloon and take it to Cliffwalker Post. From there, the plan is to unleash the payload on the Alliance at Battlescar Valley.
You better get going, <name>. It's not wise to keep Krom'gar waiting.
Speak to General Grebo when you arrive at your destination. He'll be able to brief you on the next course of action.
Chieftain Cliffwalker and his tauren seek to commit treason against the Horde! They claim that the ancient tree at the heart of Battlescar Valley is merely a school for druids. They are blind to the fact that desperate measures are taken during war time. My scouts have assured me that the night elves hide a weapon of great power within that tree. We're going to end this now!