Yggdrasil is one of the beginning places for creation and has been described by Lucifer as the focus of the lens that is creation.
In The Wolf Beneath the Tree story arc, it becomes incredibly clear that Yggdrasil somehow relates to a method of ending creation, which is the goal of none other than Fenris the Wolf. When Lucifer Morningstar learns of this he becomes worried, or so it seems, and decides to intervene in the fate of Yahweh's abandoned universe as it might even effect his own.
So he flies off to Heaven where he warns Uriel and The Host, but none of them seem to understand. So instead he wakes Michael from his task and takes both his brother and Elaine with him to Svartalfheim which is where he claims Yggdrasil expects to be approached from, making it the easiest route.
Fenris of course has a much easier way, by using Charlie Gilmour as the chariot, Charlie must lose himself, both physically and mentally, giving up memories and body parts to make the journey whilst Fenris, Abonsam and Bet can simply follow behind him and remain unharmed. This journey takes a huge toll on Charlie, making him even forget the names of his wife and child, the only reason he had even agreed to The Wolf's bargain.
After Fenris, Abonsam and Bet Jo'gie have used Charlie Gilmour to arrive at Yggdrasil and then ordered him to kill his wife and child, The Wolf decides to explain to Charlie why it is that all of this will destroy creation. The truth is that, Fyrir Haft, the slaying of one's own kin, is the first and worst of all sins and as such is the breach through which nature bleeds. So, if the roots of Yggdrasil should drink up the blood of those slain by their own kin, oblivion would be assured for all creation.
Michael, Lucifer and Elaine of course arrive at Yggdrasil the hard way in order to prevent this from happening but by the time they arrive it is seemingly too late as they are simply used and it is actually Lucifer's slaying of Michael that does what Fenris had intended for the Gilmours all along. As Michael dies though, he releases the Dunamis Demiurgos and Yggdrasil is seemingly destroyed by the expulsion of power.
In ancient time the realm of Asgard was a vast wasteland of ice. Then the Ymir and the frost giants appeared along with a magical cow named Auðumbla. The cow licked the ice until Buri, the first Asgardian was born. Buri had a son named Borr and Borr, with his giantess wife Bestla, had 3 children named Odin, Vili and Ve. Odin and his brothers grew up to defeat Ymir and his frost giants. Following the defeat of Ymir, the 3 brother plants the seed which would eventually grow into Yggdrasil, the World Tree.
The Tree grew roots all the way into the Asgardian realms of Jotunheim (the Well of Mimir), Nifelheim (Spring of Hverggelmir), and the city of Asgard where the gods lives (Well of Wyrd). The tree is said to grow golden apples which the Warriors Three ( Hogun, Fandral, and Volstagg) were once sent to capture. Both Odin and Thor have hung themselves from the tree’s branches in order to gain knowledge from the runes.
The root and wells/springs of the Tree have had varying significance also:
- Odin once lost his eye to gain the waters of knowledge from the Well of Mimir
- The root to Niffelheim also leads straight through the realm of Hel where Hela watches over the souls of the dead at the Spring of
- The Well of Wyrd, located right in the city of Asgard, is where the Norns (or Fates) reside.
- Jormungandr (The Midgard Serpent) was once said to be coiled around Midgard (Earth) at the base of Yggdrasil.
The Nine Worlds
In Asgardian (or Norse) terms, all Nine Asgardian worlds revolve around Yggdrasil. Starting at the top:
Upper Realms - Around the upper parts of Yggdrasil
- Asgard - The City of the Gods. This is where all of the Asgardians typically live. Odin rules from his throne in Asgard and the Yggdrasil root leads to the Well of Wyrd.
- Vanaheim - Home of the Vanir. These are an older sorcerous branch of the Asgardians. Asgard resident Frigga, Njord and Frey are Vanir but chose to stay in Asgard due to an ancient war between the two.
- Alfheim - Home to the Light Elves. This realm has been shown to have to extreme: First, a bright spring climate with elves that mostly resemble humans with pointed ears. There have also been times where Alfheim is a bitter frigid winterland with elves of a blue hue.
Middle Realms - Around and below the roots of Yggdrasil
- Nidavellir - Land of Dwarves. This is where the furnaces of Asgard are located. Here the dwarf Eitri forged many famous Asgardian weapons, such as Mjolnir, Stormbreaker, and Thunderstrike.
- Midgard - Earth. Home to humans, mutants, and superpowered being alike. While not directly connected to Asgard, it still falls within the axis of Yggdrasil. This realm is the second home and under the strict protection of the Asgardian god of thunder Thor. The Midgard Serpent once surrounded the entire realm.
- Jotunheim - Land of the Giants. Here one can find Frost Giants, Storm Giants, Rock Giants, and all other forms of Giants. Separated from the rest of Asgard by the Rive Iving, Jotunheim was the birthplace of Loki before being adopted by Odin. Where the root of Yggdrasil leads to the Well of Mimir.
- Svartalfheim - Land of the Dark Elves. Located at the very bottom of the middle region of the Nine Worlds below Midgard and Jotunheim.
Lower Realm - Far below the roots of Yggdrasil
- Hel - Land of the Dead. Where Hela lords over the common folk who didn't die honorably in battle, earning a place in Valhalla.
- Niffleheim - Just below Hel, but not its own separate world is the frozen wasteland of Niffleheim where the dishonored dead reside. In Niffleheim is where the last root of Yggdrasil grew to the Spring of Hvergelmir
- Muspelheim - Land of Surtur. Here Surtur rules over the fire demons in the land of eternal fire.