From publisher blurb:
Finding the Temple of the Hag is not as simple as getting from point A to point B. The dark spirits that live within keep their temples well hidden. Sword-bladed grass, quicksand, and the dreaded doomsday skeeters are only a few of the dangers that skulk along the haunted paths of the Swamp of Doom. Somewhere within, living in the shadow of the Bat-Winged Fiend himself, the mysterious swamp hag bottles her stolen souls.
This scenario is set in Scott Malthouse’s Peakvale campaign setting. While it can be incorporated into any other T&T world, such as Trollworld or Elder, we recommend that you check out Trollish Delver Games for details first. The player characters should either have Combat Adds of 50 or more or be able to cast at least a couple of 3rd level spells. It is assumed that the players have survived the [No Fences to Mend] scenario (and possibly had a few [Hot Nights in Lowhollow]), but the scenario can just as easily be played as a standalone adventure.
It should be noted that while this scenario is designed for T&T 7 and 7.5, it can easily be adjusted to any edition.