In Saving Yenniku, you must use the to capture Yenniku's soul and return it to his people. This is the final quest in a long chain, all available in Grom'gol, the first being which can be obtained from Nimboya at the north exit to the camp.
I have reshaped the Mind's Eye into a Soul Gem. Its purpose is twofold: you must use it to stun Yenniku, and once stunned place it upon his head to entrap his soul.
Then, bring the gem to Nimboya.
Yenniku dwells with Zanzil the Outcast, at the Ruins of Aboraz, along the Crystal Shore on the distant Cape of Stranglethorn.
<name>. Kin'weelay told me you set out to capture Yenniku.
Is it true? Do you have him?
You've done it! You freed Yenniku from the will of Zanzil, and completed the mission I had thought was so desperate.
Our tribe will remember your name in songs, <name>, and we will etch your tale in stone so that it will live forever.
You will be rewarded with the following:
- 500-5050 XP
- Darkspear Trolls +350 rep
Take the you get when you accept the quest and head to the Ruins of Aboraz. Yenniku[38, 58] is in the south-western corner of the ruins, almost completely alone. Simply use the Soul Gem while targeting him (you don't have to weaken him first or anything), and he will become friendly. Right click him to capture his soul in the gem and create the .