Not really a god per se, but referred to as one by some of the inhabitants of the Beastlands.
Formerly the Meat Train that moved fiends between the “lower” gate towns of The Outlands. Was hijacked by the party, who forced the train to Plane Shift to the first layer of the Beastlands, causing it to crash into the River Oceanus.
Something about the waters of that river appear to have “woken up” the brain of the train, which shortly thereafter disconnected itself from the organic cars it was hauling, and made its way up the “treeward” side of the river, disappearing into the nearby forest.
The party eventually discovered the brain of the train had shed its metallic train chasis. They also discovered it had shed the part of itself that had kept it subservient and fearful, Lymbix Thissara.
Along the way, sources of water the brain remained in too long became infected, causing animals exposed to it to mutate and become aggressive.
The brain eventually made its way to the World Ash, Yygdrasil, burrowing its way inside and slowly infecting the very tree itself. By the time the party made it to the tree (three months later), and made it to pool where the brain was “incubating,” they discovered the brain had grown a new body, something amphibious with three sets of eyes set in a column.