—Ursula, Chariot of Fire
The Yggdrasil was a huge tree of astronomical proportions, its branches encompassed the entire world and are even said to have held the stars and planets in place.
Yggdrasil grew from the seed of creation fed by the power to believe in sentient beings, humans in particular. Through its branches a special energy flowed, flooding the cosmos with it. The first witches obtained infinite magic from the tree and its energy. However, its power withered with time until all that remained was its branches, called Ley Lines. This signaled the end of the Great Age of Magic. However, the heart of Yggdrasil and the seed from which creation sprout was protected and passed down secretly among witches, a power known as the magic that can alter the world, the Grand Triskellion.
The Grand Triskellion was sealed in Arcturus Forest by the Nine Olde Witches to protect it from falling into the wrong hands (like Croix). After the Grand Triskellion was unsealed, Akko and Diana used the power of it to restore Yggdrasil, bringing it back permanently. Yggdrasil made everything around it green and prosperous.
- Yggdrasil (translated as Odin's Horse) is part of the Norse Cosmology. According to several sources, Yggdrasil is a tree of eldritch proportions, whose role is to hold the nine realms (Niflheim, Helheim (Underworld), Nidavellir/Svárftálfheim, Jötunheim, Asgard (Heaven/Realm of Gods), Midgard (Earth), Vanaheim, Muspelheim, Alfheim). Perhaps coincidentally, the number of realms matches the of the Nine Olde Witches. Their connection, if any, is currently unknown.