Oasis Hidden Gate
The tree lets out a soft sigh. 
"The Will that is Galen is no more. The Lich has destroyed [i]It[/i] and the Vessel [i]It[/i] inhabited. I am what remains. The Spirit of the Oasis." The tree says.

"So you can help us?" Raydel speaks up. 

"I have no means by which to aid you. Neither do I have the means to halt or even impede The Lich." The tree stops to creak and groan as it shifts. "There is a system in place by which Galen ensured that no other beings would be able to seize my authority for themselves. Only a Vessel may access my authority."

"So we just need to make a new vessel." Raydel states attempting to work to a solution.

"Were it so easy. Furthermore, only Galen may inhabit a Vessel." The tree muses for a moment. "There were plans to allow others, namely Lexianna, Azriel, and Cael, to access the Authority in the event of dire emergency. But [i]He[/i] never got around to establishing it."