Quest: The tree of Shadows

If the party accepts the quest from Crisophleia , they will have to get to the Three of Shadows, home of Moreka.
During the travel, they meet Lumineth . The spirit tries to dissuade them from moving on in their search for the Cave of Oblivion . He speaks to them about forces older the world itself which are a threat to every living being. He tells them that cave is protected by the most powerful spirit he knows, which is gone mad. They have no chance of getting out alive.
Then, it looks at Tarek and recoils back. He tells him that he has no idea what is inside him, that he needs to be careful, the more powerful that THING becomes, the more power it will have over him.
He then walks away.
As they get closer to the tree, the forest gets darker and darker. Animals start disappearing. Until they get close to the Three of Shadows. The Three is a massive rotten skeletrical tree, with branches with no leaves. Under the branches, s permanent darkness is projected.
The voice of Moreka is heard as they come closer. The door is shut and 8 dark purple crystals are engraved on it. As the adventurers knock, shadows appear and attack them. These are the souls that Moreka trapped and use as guardians. When the shadows die, they revert to their previous form.
When they are defeated, they can enter and meet the witch of the Shadow Tree.
She will decline their request to help the Dryad unless they do something for her. She wants them to investigate the last place where the spirit has been seen. Her friend used to keep dangerous spirits at bay, one of them is known as the Swamp spirit. So annoying that Nokdromas made his lair nearby the swamp to keep it in check. Now he is unleashed. Moreka wants them to get rid of it.
At the swamp they find the lair of Nokdromas, there are traces of fights and the silver blood of Lumineth. The swamp is surrounded by demons, on the ground the body of a dwarf, on it, the Letter on Dwarven body.
If Thorgrimm touches something, he has a vision of Lumineth and Nokdromas fighting.
Once they get back to Moreka, if they tell them about the vision, she will perform a ritual to understand what happened.