From The Heretic Knowledge Vault
The structure of the Veracian Church as it exists in the Errant Road-verse hasn't been fully developed yet, but apparently there is an "Orthodox" main line and then a number of minor denominations that are, well, unorthodox. The Malletarians are derived from one of these not-quite-orthodox branches that spun off some time in the past, then did things that were so repellent to the Church as a whole as to get themselves anathematized. The specific "things" responsible for this expulsion haven't all been revealed, but certainly prominent among them is the highly heretical belief that Luminosita is a death god who must be appeased through human sacrifice. It's certainly understandable how this little bit of dogma might be damaging to a denomination's image. The Malletarians were booted out of Veracia some time in the past, to seek refuge in Farrel, nurse their grudge, plot their vengeance.
At game time, the main Malletarian presence is in a secretive compound high in the Mountains of Madness in north central Farrel. Player characters Jamie, Marcus, Grope, etc., stumble across this encampment while on their journeys into and through the mountains. Most are on the receiving end of gunfire, offensive magic, or both, although as yet there haven't been any fatalities among the PCs. (It certainly hasn't been for want of the Malletarians trying.)
As if that wasn't bad enough, the Malletarians have somehow infested a few sites in Veracia, where they have emplaced teleportation traps, apparently something distantly resembling elven travel platforms, except one-way. These are used to procure sacrificial victims to offer to Luminosita, the Malletarians quite sensibly preferring that the blood shed to appease the god be someone else's rather than their own. One of these traps is in the ruins of Centoriel, scene of a visit by PCs Argus, Sasha and Lillith as well as semi-PCs Sister Rose and Brother Miguel. This trap has scooped up the unfortunate Liz and Wilbur Hamael, the latter of whom survives (at this writing) in the compound in the Mountains of Madness.
All told, these are definitely not among the people you'd really want as next-door neighbors. Then again, following the eruption of the volcanic Dwarven Forge, their compound looks to have been wiped out, and possibly, all of them along with it ... or not. Stay tuned.