Spirit Crucible Elpys

Spirit Crucible Elpys is an area in Xenoblade Chronicles 2. It is a series of caverns inside Fonsett Island of the Leftherian Archipelago with little Ether flow. Due to the scarce Ether flow, other than Poppi, Poppibuster, Shulk, Fiora, and Elma, Blades cannot rise above certain levels of, and can only use up to a certain level of Blade Specials (the exact level of each depends on the location within Elpys - for most of the area, only level Specials can be used).

Geography
Spirit Crucible Elpys is located within the central Titan of Leftheria. Its main entrance is on the outskirts of Fonsett Village, and the door will only open to Leftherians, much like the seal on the Ancient Vessel. The Spirit Crucible itself is comprised of various dimly lit caverns, and notable ancient Tornan architecture at various points. As the cave gets deeper, the ether flow becomes more and more restricted, limiting the combat potential of Blades, whom primarily draw their ether supply from the atmosphere. While the original purpose of the Spirit Crucible is not known, it had been repurposed by Addam to house the third Aegis Sword, and test the resolve of Mythra's eventual true Driver, an honor Addam felt unworthy of. Both by the aforementioned seal, and a later seal that none before Rex had passed; enormous green crystals blocking a cavern that went deeper into the cave.