Doomwalker
The Doomwalker ritual is performed by orcish communities who have collectively sinned against Gruumsh. A single individual volunteers to take on the sins of the entire community, after which they are exiled. Henceforth they are known only as "Doomwalker," frequently forgetting their true name in the process.
The Doomwalker must seek atonement for all of the sins that have been placed upon their soul; as this typically involves slaughtering large numbers of Gruumsh's foes, Doomwalkers rarely survive for long. Additionally, other orcs and half-orcs will recognize a Doomwalker on sight, and clerics of Gruumsh will gain knowledge of the specific sins placed upon them; in both cases they will typically attempt to kill the Doomwalker.
An unusual case occurred with the orcs of Garlandar; after being freed from slavery under a clan of hill giants, the orcs decided that it was the worship of Gruumsh that ultimately led them to that state. As part of their renunciation of their former god, they adapted the Doomwalker ritual to be directed at Erathis instead, absolving themselves of all the bloodshed they committed in Gruumsh's name by placing it on the half-orcs Sharog.