Originating from the Alien God's seeds, the Fantasy Trees appear to be integral to the Lostbelts. They contribute to the Lostbelts overwriting the Greater History of Man, a phenomenon called the Filtering Alternate History Phenomenon. If the Fantasy Tree of a Lostbelt is destroyed, the Lostbelt itself crumbles as well.
Destroying the Trees is apparently very difficult. Though the first was destroyed by the Priestess of the Alien God, Chaldea was able to destroy the second one only thanks to Surtr consumed a part of it, weakening it. Under normal circumstances, Chaldea would not have been able to destroy the Fantasy Tree alone.
As the Fantasy Trees mature, they are able to expel seeds, Fantasy Tree Seeds (空想樹の種子-, Kūsōju no Shushi?, alternatively referred to as the 'Seeds of Fantasy'), which appear akin to alien monsters.
The tree recognizes a single individual within the Lostbelt as the King of the Lostbelt (異聞帯の王, Ibun-tai no Ou?) and grants them certain authorities to reshape the Lostbelt's environment and expand its domain by interfacing with the local leylines.
Fitting their unearthly origin, the Fantasy Tree designations appear to be derived from astronomical objects, such as star systems and galaxies.
At the end of 2017, around the same time as the assault on Chaldea, several mysterious objects descended from the sky on an unnatural vertical trajectory. When they impacted, the Earth's surface was rendered white, turned into a 'blank slate'. At the same time, the Fantasy Trees manifested within the Lostbelts.
During the time in which the Lostbelts were woven onto the planet's surface, the Crypters which had been assigned to the Lostbelts carried out their task of nurturing the trees and building up the foundations of their domains. After the three month long process, they prepared to compete against one another to decide which Lostbelt would survive to form a new history and a new world. At the same time, the survivors of Chaldea, who had previously escaped into Imaginary Number Space aboard the Shadow Border, resurfaced in order to fight back against the invaders.
At the time of Chaldea's arrival, Orochi was the only Fantasy Tree to have not properly taken root and started budding. As Ivan refused to use the authority he been granted over the tree, given that the tree originated from a foreign god, and didn't permit it to interfere with the ley lines, Kadoc and his Servant Anastasia sought to depose him, so Anastasia could assume his authority over the tree.
They eventually succeeded in overthrowing Ivan with assistance from Chaldea and Anastasia had the tree begin to spread its roots, shortly before their defeat at the hands of Chaldea's forces. After Anastasia's death, the tree began to emanate a huge quantity of mana that, according to Da Vinci, was close to True Ether and could revert the logic of the planet back to the Age of Gods if the tree wasn't stopped. Chaldea moved to destroy the activated tree, but while they were able to silence it, they weren't able to fell it. Instead, it was destroyed by the Priestess of the Alien God. Afterwards, the pseudo-Holy Grail left behind in the remains was collected and stored in Mash's shield
Unlike Orochi, Sombrero had spread its roots and was releasing seeds, though Scáthach-Skadi wasn't able to fully make use of her authority over it and the tree's capabilities, due to having to maintain the seal on Sutr.
After Sutr broke free of the seal, he absorbed the tree in order to regain his lost power. Following Sutr's defeat, the tree was left in a weakened state, which allowed Chaldea to destroy it.
Mayall (メイオール, Meiooru?) was the Fantasy Tree of the Chinese Lostbelt, supervised by Hinako Akuta. Its chosen king was Qin Shi Huang. Following many defeats it was discovered by Qin and Hinako allowed it to absorb her, which awakened it. Once defeated once more, Hinako was expelled from it before disappearing at the hands of Chaldea.
Atlas (アトラス, Atorasu?) is the Fantasy Tree of the Lostbelt supervised by Kirschtaria Wodime. The tree shares its name with the Titan who is said to hold up the heavens in Greek mythology. According to Kirschtaria, its roots cover approximately eighty-percent of the Planet.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 22
- ↑ 2.0 2.1 Fate/Grand Order - Second Prologue, Part 8
- ↑ 3.0 3.1 3.2 Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Prologue
- ↑ Fate/Grand Order: Cosmos in the Lostbelt: Gotterdämmerung info summary by Fallacies at Reddit
- ↑ 5.0 5.1 5.2 Fate/Grand Order: Cosmos in the Lostbelt - Gotterdämmerung: Eternal Ice-Flame Century, Chapter 17
- ↑ Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 5
- ↑ 7.0 7.1 7.2 Fate/Grand Order: Cosmos in the Lostbelt - Gotterdämmerung: Eternal Ice-Flame Century
- ↑ Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 1
- ↑ Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 12
- ↑ Fate/Grand Order: Cosmos in the Lostbelt - Anastasia: Permafrost Empire, Chapter 20