A One-Round Living Greyhawk Verbobonc Regional Adventure
From the introduction:
Dragged away from a peaceful night to fight in the war for the Iron Wood, the characters must choose their allies carefully and keep the Great Dire Dark from eclipsing the entire forest.
Decisions the characters have made earlier in the Glory Trilogy will affect their fate in this scenario. This climactic battle is Part Three of the Glory Trilogy, which should be played in order.
An adventure for [character levels] 4 - 12.