Simple addon that announces in general (therefore Stormwind or Orgrimmar), when the Doomsayer you are talking to has the second dialog option, summoning a Dread Infiltrator.
It announces your location (by SubZone and coords)
DoomsayerSayer also informs you if you are interacting with a Doomsayer without an ability to track demons active
1.03 [19-Aug-16] - Fixed an error when opening Architect/Shipping tables
1.02 [19-Aug-16] - Will no longer repeat in general if you interact with the same ready Doomsayer multiple times
1.01 [19-Aug-16] - Added right Doomsayer NPC ID for Horde!