The Demon Heart of the Deathtree

From the introduction: Many generations ago, this Tree was the heart of the Elven Kingdom. However, the demon Yad deceived the elves and corrupted the Tree. The elves fled, and only through their ultimate sacrifice could the elven wizards contain Yad's evil, banishing him back to the Abyss. The forest was left uninhabited, and the stories of ancient curses made it a place to avoid.