Additionally, if you'd like to learn more about farming Mephisto check out my Mephisto Farming Guide. If you'd like to learn more about farming the Durance of Hate I recommend heading over to my Durance of Hate Farming Guide which will tell you all you need to know about this dungeon. In addition to this, the Durance of Hate Level 2 is one of the largest zones in the entire game which is great for farming but terrible if all you want to do is get to Mephisto and take him out. The Durance of Hate makes a very good farming location since the entire dungeon is level 83 in Hell which is one of the highest area levels in the game (meaning it can drop almost every item in the game). Both of these quests complete the moment you destroy the Compelling Orb next to the Durance of Hate's entrance. In order to gain access to the Durance of Hate you'll first need to complete Act 3 Quest 3: Khalim's Will as well as Act 3 Quest 5: The Blackened Temple. Basically all you have to do for this quest is make it down to the Durance of Hate level 3 and take out Mephisto, the end boss of Act 3.

You receive this quest automatically the first time you step foot into the Durance of Hate. Reward: Mephisto's Soulstone & Act 4 Access

Diablo 2 act 3 quest temple