Hidden by rocks by the edge of Beggar’s Gorge in Lost Lands is a noxious pit (8.10’N 39.47’W 5578, 3019). This is the entrance to the Palace of Paroxysmus. To descend into this pit the adventurer needs an acid proof rope, this can either be crafted by a carpenter or bought from Lucius the adventurer, who stands near the entrance, for the modest sum of 5,000gp in hard coin (mark the pile of coins as a quest item)
The first thing encountered in the dungeon is the noxious river of acid which runs all through the caverns and possibly an acid elemental or earth elemental. A path runs alongside the river, but following it will lead only to an exit (image below), more acid and earth elemementals, and a dead end. Instead cross the river using the stepping stones to avoid being damaged by the acid.
The path beyond the stepping stones sees the addition of corrosive slime, plague spawn and poison elemental to the encountered inhabitants. The corrosive slime are one of the holders of the keys needed to access the peerless commander of this domain, Paroxysmus. The path crosses the river again where it falls into the cavern below, this time on a stone bridge. On the lower level plague beasts add to the mix of hostile spawn and stepping stones provide another needed crossing for the river. Following the river leads to the only area of building in the dungeon, guarded by two pillars topped by gas traps. Molochs, arcane daemons, daemons, succubus and balrons wander among fallen stone walls, jail cells and a raised dais apparently used for sacrifice. Here, too, is a poor lost villager, Kodar. He would appreciate your help to leave.
The town can be avoided by keeping close to the mountain and walking along the side of the river for a short distance, arriving close to the exit gas trapped pillars of the town, but fortunately not too close. Staying close to the river and negotiating spawn that now includes the additions of succubi, daemon and plaguebeast lords, will eventually cross a final set of stepping stones and lead to the cauldron that is used to reach Paroxysmus himself. To reach the lair of the Named Creature, Putrifyer; also a holder of Paroxysmus’ keys, one must leave the river and turn south shortly after passing the town.