The gods have spoken and we must heed their wisdom.
Gather friends to your side, <name>. Take them north to Zim'Rhuk to destroy guardians there until they yield the unblemished heart. Take them southeast to the Altar of Quetz'lun and disrupt the altar wardens until you recover their gusty essence.
Deliver both to Har'koa and she will combine them into that which will compel late Akali's prophet to appear.
Progress
Do you have that which is required, <name>?
Completion
Your bravery seems boundless, <name>.
Please hand me the heart and the essence, and I will fashion them into that which compel the prophet to appear before you.
Notes
Since the mobs at the Altar of Quetz'lun are neutral from an earlier quest, you don't have to worry about aggro ranges. Patrolling mobs will aggro the ones you fight once you come close, though.