Black Rook Missive
The Black Rook Missive is a reward from the rare class hall mission Investigate Black Rook Hold. There are three identical versions for Normal, Heroic, and Mythic difficulties.
While it turns up from time to time in your mission queue, it will probably be quite some time before you'll get your followers' ilvl high enough to actually do it.
- Patch 7.0.3 (2016-07-19): Added.