Ranker's Purgatory
Jules needed Eren's presence as an anthrope to open purgatory.
A ranker's purgatory, or just purgatory, was similar to a ranker's utopia in many ways. It was a separate dimension created by S-Rank entities in their final stage of the rank to choose their successor by testing their mettle.
But unlike the ranker's utopia, a purgatory was created by heretic rankers of their time now known as cultists. A purgatory was much more brutal and dangerous to explore than a utopia. Purgatory exploration usually results in heavy casualties.
But these risks carried substantial rewards. A purgatory usually contained the S-Rank entity's complete inheritance. High-ranked heretic rankers of their times would rob and plunder all the riches they could find. And then they would dump all their loot in the separate dimensions they created.