A Sticky Ordeal

From the introduction:

Uncover the secret of the mires of Grull, a once-thriving forest that non dare enter.

Publisher's blurb:

Many generations ago, the once prosperous Forest of Grull suddenly became a land of death and disease due to an unknown cause. This event is known to historians as Terra Shorn, or the Unhollowing to locals.

In the present day, few dare to travel into the Mire. The swamplands include a clan of Bullywugs who worship and provide for their leader, a Froghemoth named Gourp. Additionally, there have been rumors of an ancient Hag who has existed since the Unhallowing. This Hag, Grenda, stole the Essence of Life from the local spirits in order to gain immortality and continue her unholy research.