Map of Avernus

Some additional info on places you've been or know about:

• The green blob that stretches across part of northwestern Avernus is the Pit of Shummrath, a pit fiend punished for his crimes by being converted into a valley full of sentient green slime into which the River Styx flows, slowly eradicating his memories.
• A5 is home of Warlord Kolasiah and their gang, the Lost Golgari. Allegedly they have a forge that may contain astral pistons.
• B2 is a Ferryman's port, where people can pay to go across, or more rarely up/down, the Styx.
• D2 (south of the river) is the base of Warlord of Avernus Carol d'Vown, aka "that bitch Carol." There may be a way across the river here.
• D5 is a gigantic helmet that serves as the shop of Uldrak the Tinker. Uldrak had astral pistons in stock once when Mad Maggie needed them, and might still have some.
• E4 is allegedly where a foundation to a tower exists; Mordenkainen himself is said to teleport his tower to Hell sometimes and recruit fiends for various information and goods-gathering.
• F2 (it is not especially clear on which side of the river) is the Purple City. Not much else is known about it.
• G5 is the site of a highly-guarded bridge across the River Styx.
• H2 contains an Avernian forge run by Bel, the former Lord of Avernus. Avernian forges may be a source of astral pistons.
• H3 is Elturel. It is attached to mechanical devices on each side of the river by gigantic chains.
• H5 is allegedly the location of a crashed Nirvanan ship. If true, it might contain a Nirvanan cogbox.
• I4 is Fort Knucklebones. Home of Mad Maggie and her gang.
• I5 is the Spawning Trees. Krikendolt remains here with his pet abyssal chicken Earwax.
• I6 is allegedly the location of a tower either in or on the Styx (reports unclear) that might be a way to cross it.