Eldergleam Sanctuary is an underground grove and worship site of the followers of Kynareth. This site is renowned for its remarkable beauty and a giant tree named Eldergleam. Eldergleam is said to move its roots for one weapon only, according to Asta.
Fast travel to Windhelm and travel south. It’s a significant distance, so make sure you are unloaded and ready for a few fights here and there with wildlife and bandits. Best to scout ahead and clear a path so you don’t have to worry about playing babysitter. You’ll find the cave leading underground. There are about 6 Dragontongue flowers around the front.
The only way to clear away Eldergleam’s roots and allow passage to the tree itself is by hitting them with Nettlebane.