Many of the densely-packed monsters on the ground had Detection abilities. The sky above was also dotted with all kinds of creatures. If he didn't have the Eyes of Grillok, he simply couldn't keep going.
It would be perfect apart from the fact that it could only be used for 20 minutes at a time, and it could only be used three times.
He was originally going to find a Warlock to notify him of what the enemy was up to, but he had no way to ensure their safety. After all, the Warlock couldn't hide himself.
Warlocks also had a similar skill called the Eye of Kilrogg.
They were all members of the Bleeding Hollow Clan (a.k.a. The Bleeding Hollow). It seemed like this clan were all able to dig out their own eyes and use it for casting spells.
Following the wishes of his injured, diseased father, Kilrogg Deadeye complied with the clan's ancient tradition – starting a ceremony to sacrifice one's own left eye in order to see one's future fate.
