While very clearly an “evil” faction, Avowed allows you to express support for the Steel Garotte’s fanatical approach, and anyone on a villainous playthrough will want to leave them undisturbed.

Forja Quarry in Avowed's Galawain's Tusks region ... The letter is found next to a body outside an abandoned farm in Warden's Rest, which is haunted by a few powerful skeleton enemies.