Services of Dagg

To get [npc=79492] as a follower you need to release him from 2 cages in Frostfire Ridge, the first cage is at 39.52, 28.06 and the second cage is at 65.85, 60.84.

/way 39.52, 28.06
/way 65.85, 60.84.

Once you have done that [npc=79492] will appear in your Garrison with the quest Services of Dagg.

Good luck!

I believe you must find dagg several times before he appears at your garrison.
I first found Dagg at 66, 61 in Frostfall, just northwest of Grom'gar.
The second time I found him was in the Daggermaw Ravine, at 39, 28. This was roughly 2-3 minutes after I found him the first time (I was actively looking for him).
After this I ported back to my garrison and found this surprisingly charming ogre waiting for me, just outside the northern garrison gate!

The Master of Dis Guys.