Quetz'lun's Spirit at the Altar of Quetz'lun wants you to use Quetz'lun's Hexxing Stick upon High Priest Mu'funu, High Priestess Tua-Tua, and High Priest Hawinni. Once you have done this, slay them.
1x High Priest Mu'funu hexed at death
1x High Priestess Tua-Tua hexed at death
1x High Priest Hawinni hexed at death
It is now time for you to punish my three high priests: Mu'funu, Tua-Tua, and Hawinni. You'll find them spread around the altar grounds.
Take this hexxing stick. I've empowered it with my rage and indignation. I'm sure that it will prove potent.
Just use it and proceed to destroy them. The hex will take care of the rest.
<Quetz'lun displays a toothy grin.>
Succeed and I may let you go. Fail and die.