Learnings: The Well of Mimir
Eons ago, a great war shook the World Tree to its roots. Divine armies of different realms clashed on the battlefield. Eventually a truce was called and hostages were exchanged to keep the peace. One of these hostages was Mímir, a god of knowledge and intelligence—and a good friend to Odin, the All-Father.
Mímir's time as a hostage ended badly when he lost his head—literally. His captors sent the head back to his friend Odin, who preserved it with magic. Odin's skill and power allowed Mímir to remain alive as a head without a body.
Mimir was placed beside the well at the bottom of Yggdrasil, seen here in artistic sketches for Assassin's Creed: Valhalla. There, he could oversee the magical waters and make sure that no one drank them without paying the price.