Acheron is a harsh plane where giant blocks drift together and apart. Between all is an atmosphere, yet though the blocks move relative to one another, there is never any wind.
The Infernal Battlefield of Acheron is a plane which exists on the Evil side of Lawful Neutral on the cosmological wheel of the multiverse, though not actually evil because it represents a plane of existence where imposing order and conformity is more important than morality or reasoning, to the point that you are just one more faceless pawn who gets played in a pointless struggle that never ends.
Avalas is the battle plain universe, where armies from all eras and all planes dominate societies that are always at war. The blocks are made of hard metal. The orcs and the goblins fight eternally on one of these blocks. The urbane rakshasas control much territory on other blocks.
Vorkham, “the City of Fumes”, is a city made of titanium with acid fountains. The Mercykillers has its headquarters here. Those without a strong constitution may get sick just from the environment. Mercykillers are immune. There is a Gate from Sigil into the city. There are three gates through the defensive wall out to the surrounding plane: the Lion, Wolf, and Hawk gates.
Savrin's family have their iron mines located about a half day's journey from Vorkham. They hoped to make a fortune by shipping it to the Abyss during the iron shortage caused by the razing of Raazorforge. (28,29)
Team Pelor was hired to rid the mines of a Rust Dragon after it attacked and ate many of the miners who were invading its home (36)