Walkthrough for the "Tribes of the East" expansion.

It's a bit frustrating to read that everyone has already made significant progress in the game, while I'm stuck on the second campaign – where I need to find the two halves of a key. I've already obtained the first half, which is guarded by astral dragons. Then I searched the entire map, killed everything that was on it, and defeated the red dragon, even though he didn't attack me. But the key is nowhere to be found! I've already drooled all over my monitor. And the worst part is that there's a time limit; I need to complete it within three months. Please tell me where the second half is.