Yester Hill

Yester Hill is an ancient druidic site in western Barovia. Once a mass grave heaped with earth, this cairn has become a hill on which an ancient, twisted tree grows. Barovia's mountain clans have long used the hill as a site for druidic blood rituals. The druids who worship Strahd as lord of the land and master of the weather convene here, atop Yester Hill, on the very edge of Strahd's domain. This hill is also where the evil blights that walk the Svalich Woods are born, and where Strahd comes on occasion to glimpse his ancestral home.
After their departure from the Kavani tribe, the druids of Yester Hill continued in their descent into darkness. Their connection with nature—while strained—remained with them, and they often took on the shapes of forest animals for ritual purposes. This changed when the druids began to cultivate a Gulthias tree that they discovered in the forest. At that point, darkness truly took hold within them, severing their ties to the natural world around them, and the ability to change their shape was lost.