Nemeton
It had guardians once, a long time ago. So long that human beings have forgotten, but the tree does not forget. The tree is old and its memory long.
For years, it hides in its roots,. two door ways one to the hevens and other to hell, a power of great chaos. It understands why the young woman hid the jar there. She had already sacrificed something dear to herself, and so the tree lets her do as she will. Maybe she'll be back to care for it later.
More years pass. People make weapons of its branches, of its blood-sap, try to destroy it for their own ends. But something so old and powerful cannot simply be cut down and forgotten. The cutting down of the tree closed one doorway to words Heaven, cutting off lara and Thena away back home, leaving them stranded on earth in Beacon Hill.
The two young goddesses can tell that the Nemeton lives on. In slumber sometimes, in dormancy. But even then it dreams of better times, of its guardians who loved and cared for it, and when it awakes again it was because of love.
It remembers the werewolf boy and his sick human mate. It's heard whispers of explanations later, that the blood sacrifice of the girl is what brings it out of dormancy, but they are misunderstandings, misdirections. The tree knows what woke it, and it was not blood. It was love.
The tree had guardians once, and they loved and cared for it, making sacrifices of love and time and labor. It has never forgotten, and it yearns for such guardians again.
When the werewolf boy sacrifices his own innocence for the love of the girl, the tree wakes. It waits for the boy to come back, to care for it. To make it live once again, to give it branches that reach to the sky and soak up the sun again. Its roots are strong. It can live again with proper care. And so it waits for its new guardian.
The boy does not come back. The tree is not aware that the boy and his entire family had been nearly wiped out and fleet Beacon Hill for their safety.
Instead, there is a druid. She is near death. She makes promises, if only she can live. She will care for it again, she will give sacrifices. The tree has been so lonely, has missed its druids so much. It doesn't have much power right now, but it is enough to heal the desperate woman. The tree is patient. It can wait.
The druid, the sacrifices — they are not right. Everything is twisted and wrong now, and while the tree is definitely getting stronger, it feels sick. Dark. It gives her the gifts she asks for, but the tree is not happy. It remains unfulfilled. There is no love, no caring. No prayers other than twisted spell-words the druid has bastardized to her own ends. She is not druid, not really.. She is evil, black magic, and she is poisoning the tree with her unwilling death magic sacrifices.
Some days, the tree cannot even remember the old guardians, the happier times. The druid has twisted even those memories. Instead, her thirst for blood and revenge begins to seep into the tree. It begins to crave new things it shouldn't.
Once of vibrant tree now with it with darkness and evil, with such power the doorway to hell remained open. Allowing chaos and Darkness to rampage through Brecon Hills.