Bring the Filled Egg of Hakkar to Yeh'kinya in Tanaris.
Now it is time to capture the essence of the avatar of Hakkar.
Take the Egg of Hakkar to the Sanctum of the Fallen God in the Sunken Temple in Azeroth. Invoke the egg's power to stir the dead god.
He will send his minions against you. Defeat his bloodrinkers and take their Hakkari blood, then use the blood to dowse the eternal flames that hold Hakkar's spirit. When all the flames go out, the avatar of Hakkar will enter our world.
Defeat him, and place his essence within the egg of Hakkar.