Outer Steppes (Act 4) Farming Guide - Diablo 2
How to Reach: The Pandemonium Fortress > Outer Steppes
Zone Level: Nightmare: 56 -- Hell: 82
Golden Chest: No
Boss/Champ Packs: 1 - 6
Hell Immunities: Fire (Doom Knight, Venom Lord, Balrog), Cold (Flesh Spawner & Flesh Beast), Lightning (Cliff Lurker & Doom Caster), Poison (Corpulent)
Outer Steppes is one of the outside/field areas in Act 4 and is the first area you step foot into when you leave the Pandemonium Fortress. This area along with Plains of Despair and City of the Damned are the 3 highest Area Level field zones in the entire game. What I mean by field is basically a wide open zone, not a dungeon. Some classes/builds do much better in open areas like this than in dungeons, like Bowzons. The River of Flame is a zone I would consider a field too due to how open it is; and that zone comes with the added benefit of being a level 85 area.
Throughout these zones you will still have pillars in your way and other obstacles along the landscape but for the most part they are much more open than any dungeon that you'll find. Another thing worth mentioning is that in this zone and basically every other one in Act IV you should expect extremely high mob density. Similar to the start of the game in Cold Plains, Blood Moor and all of the zones with the massive Fallen packs.
If you are farming for the highest Treasure Class of items then the high mob density will only be a hindrance to you; for people who aren't being as picky when it comes to loot--then it'll be a nice boon in your favor. High mob density is extremely beneficial for people looking for High Runes since High Rune drops aren't affected by Magic Find. All that matters for High Runes is mob density and mob level.
When it comes to enemies Outer Steppes doesn't have very many that you need to watch out for. Corpulents probably hit the hardest but their worst attacks can be easily avoided, the rest of the enemies are mostly just annoying. If you're hunting this zone for regular enemies and aren't solely interested in the Boss/Champ packs I encourage you to explore the outskirts of the zone too as you'll typically find a lot of regular enemies here.
From my experience hunting this zone I almost never found Boss/Champ packs around the edges of the zone. They were almost always more towards the middle or around the entrance/exits of the zone. Keep in mind that if you encounter a Champ/Boss pack in an area that's inconvenient for you (like with a lot of walls) you can always pull them away from that area to an area that's more open.