Now it comes to this. We will bring Goc forth from his lair, and we will destroy him. With Goc dead, the Bladespire ogres will threaten the Mok'Nathal no longer. Go to Goc's altar outside Gruul's Lair, then blow my horn. I will come, and we will face the son of Gruul together.
Details
The Altar can be found at location 64,18.
Rexxar can tank Goc effectively but you will need to do at least 50% of the damage to get credit for the quest. Goc does an AoE "Ground Smash" attack that does a significant amount of damage.
This quest can bug out if you take too long to defeat Goc. You might need to get a Game Master involved to reset it.
Only through the deaths of Goc and Gorgrom the Dragon-Eater will we free the Mok'Nathal.
Completion
The battle was hard and you fought well, <name>. I am honored to have stood by your side in the battle against Goc. I am thankful beyond words.
The Mok'Nathal should know of these great defeats, but I am not ready to face them yet. I know my father's mind, and I know my heart. There is still much I can learn and do to become stronger, to show to him that I am his true son.