Grulloc Has Two Skulls has you kill one of the Sons of Gruul and retrieve his skull, he is located almost next to Mog'dorg the Wizened, the quest giver. This is a group quest as Grulloc has the tendency to hit very hard.
Retrieve Grulloc's Dragon Skull and deliver it to Mog'dorg the Wizened atop the tower at the Circle of Blood in the Blade's Edge Mountains.
The skull can be looted by anyone regardless of whether they participated in the kill (even from opposing faction). The skull lasts around 3 minutes.
To the east, at the terminus of Dragons' End, is the Cursed Hollow. Therein, Grulloc, son of Gruul, plots his dimwitted schemes.
I heard that one of his possessions was stolen from him through trickery. Was that you? Unfortunate that he was not slain in the process.
If we are to regain our freedom, I would have you take his most prized possession, a dragon skull from when he rejoiced in his father's slaying of the Black Dragonflight. The only way you'll get the skull is to vanquish him.
Is Grulloc no more?
Indeed, it must have been a difficult struggle, <class>. I feel greatly relieved now that he will not be breathing down our necks here.
I will send this skull down to Chort for safekeeping. I'm beginning to think that with your help, we might just pull this off.