Mephisto (Act 3) Farming Guide - Diablo 2
How to Reach: Durance of Hate Level 2 (WP) > Durance of Hate Level 3
Zone Level: Nightmare: 55 -- Hell: 83
Golden Chest: No
Boss/Champ Packs: 1 - 3
Hell Immunities: Cold (Blood Lord), Lightning (Super Uniques)
Mephisto is one of the most commonly farmed bosses in the entire game, probably the most common - especially at the start of a new Ladder. The reason Mephisto is so commonly farmed is because most classes with AoE can very easily beat him without taking even a single point of damage by using the "moat trick".
The Moat Trick is when you agro Mephisto and Teleport across the moat to get him stuck on the other side. You can then aim your AoE at the stairs next to the moat and it'll hit Mephisto who is stuck trying to get across. Use my screenshots below for further guidance on exactly what I mean.
Only certain classes/builds are able to do this, the class/build who is arguably the best at it is Blizzard Sorceress. Since you'll barely take any damage when farming this location it's easy to load yourself up with as much Magic Find gear as you can while farming.
In the screenshot above, you'll be able to see the exact location you will want to Teleport to and where Mephisto gets stuck at. In the upper left hand of the screenshot you'll see Mephisto who is currently running into the stairs of the moat but unable to cross. He'll be stuck in this location the entire fight and will occasionally fire off an attack or two; most of the time though he'll keep trying to run over to you but fail because the moat is in the way.
Typically you'd cast Blizzard on the stairs where Mephisto is running and it'll hit him. Anyone doing this trick without the Blizzard ability can fire off whatever ranged attacks they have in Mephisto's direction. Some may miss and it may take longer to defeat him than it would take a Sorceress but it'll still work.
Before you take on Mephisto it is recommended you clear out the entire floor of enemies. You'll find enemies in each of the two rooms on either side of the portal to Act 4 as well as in the central room to the south of the portal. See the screenshot below for more information.
Durance of Hate Level 3 Map Locations.
On the third floor of the Durance of Hate you'll typically find two or three Champ/Boss packs along with Bremm Sparkfist, Maffer Dragonhand and Wyand Voidbringer. These are the 3 Super Unique enemies that you'll find on this floor and they're all marked on my map above with a 1, 2 and 3. Each of the Super Unique enemies are Immune to Lightning on Hell difficulty and they all use the Flame Hydra ability, can heal their allies and are Lightning Enchanted.
The blue circles on the map above are each of the locations that I personally have seen a Champ/Boss pack on this floor. It's fairly often that you will be fighting a Champ/Boss pack along with one of the Super Uniques since more often than not they'll spawn in an area next to a Super Unique. For more information about the Mephisto boss fight check out Act 3 Quest 6: The Guardian.