The complicated rules of time travel in Avengers: Endgame, and the end result of the actions of The Avengers, have raised a great many questions about the MCU moving forward.
It turns out the Ancient One’s return in Avengers: Endgame was a bit of a complicated process, but one that was extremely crucial to the end product.
Hulk is tasked with getting the Time Stone from the Ancient One, which proves to be rather complicated.
Specifically, if the stones are not put back, the Avengers could create splintered, alternate realities, in which, horrible things happen.