- Talk to the priest Orthenir.
- Activate the wardstones.
- Return to Orthenir.
- Enter Ilmyris and find the Hall of Memories.
- Activate the Hermaeus Mora's shrine.
- Defeat the souls.
- Find a Bosmer soul.
- Watch the vision and receive the reward.
Orthenir explains that the forest is reacting to an imminent Daedric invasion. For this reason, it has raised its protections. To fully protect the grove, the priests asks the Vestige to activate three wardstones that will hide the area. However, this will not be able prevent the invasion.
Orthenir will reveal that this daedric invasion is caused because the grove is the location of Ilmyris, the secret library of hidden knowledge dedicated to Hermaeus Mora, who is known in the Bosmeri Pantheon as Herma-Mora, or the Woodland Man. Orthenir is one of his followers, and is a member in a cult known as the Wooded Eye.
Inside the Ayleid temple, Saromir is found next to a shrine, which has been completely demented for the high use of the Ayleid crystal. Upon activating it, Herma-Mora will appear and ask the Vestige to defeat the four souls of his servants roaming into the library. In return, he will help protect the grove against the daedra with their energy.
After defeating the Khajiit, Altmer and Imperial souls, the Bosmer soul will escape, and will require a replacement. The Daedric Prince will ask for Saromir's soul, a task that can be denied. If accepted with a high enough persuasion skill, it is possible to ask him to sacrifice himself. If denied, Hermaeus Mora will choose another soul, which will be Orthenir.
After choosing, Herma-Mora's reward is a vision of Veiled Heritance leaders, which forces every member of the Wooded Eye into the Ayleid crystal to reveal secrets that would help Naemon after his resurrection as a lich, and thus leading the usurpers into finding the Heart of Valenwood.