Mictlan
Aztec Planar Pathway, also called Chiconauhmictlán
While the Styx connects the lower planes and Oceanus connects the chaotic planes, Mictlan is a path between the lawful planes, making a few other stops along the way. Starting in Mictlan (the Aztec realm of the dead, not the pathway) in the Gray Waste, the path continues straight to Baator, followed by Acheron. After stopping briefly in Huitzilopochtli’s realm on Avalas, the path travels for miles and miles through Ocanthus, probably the worst part of the entire journey. After this, the path jumps straight to Xiuhtecuhtli’s realm in the Outlands. Mechanus, Arcadia, and Ehecatl’s realm on Mount Celestia come next, then straight on to Arborea and lastly, Tezcatlipoca’s place in Limbo. In fact, most of Mictlan is a literal pathway, made out of bricks or cobbles, the whole bit. Plus, once you’ve endured the trials at the beginning of the path, the further part is quite hospitable. The occasional petitioner at a ziggurat along the road offers travellers food and drink, mostly corn tortillas and chocolatl.
You see, the oddest thing about this path is that no matter where you get on, whether it’s at Arborea or Mechanus, you start out in the Gray Waste after only a couple minutes’ walking, flying, etc. There’s no turning back: this path is one-way, berk. It’s great for getting from the Gray Waste straight to Baator, but if you want to travel from Tlaloc’s Palace in Arborea to Mount Celestia, you have to go from Arborea to the Gray Waste, to Baator… to Arcadia, to Mount Celestia. That’s too long a trek for most. You see, the Aztec Pantheon’s big on trials of spirit and body, believing that this way assures that all supplicants are worthy of making their way to the proper plane. Even all petitioners of the Aztec pantheon have to travel this way; the only exception is Tezcatlipoca’s petitioners. The humanoid ones he whisks away at the end of Ocanthus, and the non-human go straight there. In fact, the first time that anyone steps onto Mictlan (and is of chaotic alignment) there is a 5% chance that they end up in Tezcatlipoca’s realm instead of the Gray Waste.
Source: Skypti & Alex Roberts