Secret Cow Level Farming Location - Diablo 2
How to Reach: Rogue Encampment > The Secret Cow Level
Zone Level: Nightmare: 64 -- Hell: 81
Golden Chest: No
Boss/Champ Packs: 4 - 8
Hell Immunities: None (Only Boss/Champ packs)
Secret Cow Level is one of the most famous areas in all of Diablo 2 and is a bit of a meme in Blizzard games. In order to reach this level you will need to complete the game (defeat Baal) and log out or take the Destruction's End portal so you see the screen with Deckard Cain. When you are logging back in make sure you choose the same difficulty that you beat the game on. Once you've done this you'll need to combine Wirt's Leg in a Tome of Town Portal in the Rogue Encampment to open the portal to The Secret Cow Level.
It isn't uncommon for the combine to fail sometimes, usually you have to log fully out of the game then back in if this happens to you. Or complete a quest in the next difficulty then come back to the difficulty you beat the game on and try again. I'm not entirely sure what causes this bug but I have had it happen enough times on enough characters that it is worth mentioning. There is one more thing worth mentioning too that is extremely important. So important we're gonna make it stand out all big and stuff.
**IMPORTANT** Don't #$%@ing kill the Cow King in the Secret Cow Level on the 1.14 version of the game or you can not open the portal again on that difficulty on that character. Unless you are playing on 1.13 with PlugY or on some Diablo 2 Mod that allows you to repeat the Secret Cow Level you're stuck with this really stupid quirk.
Thankfully you can easily identify where the Cow King is on each map so you know to avoid him. When looking at the map keep an eye out for the structure shown in the screenshot below. The Cow King will always spawn inside or out front of this building with a few groups of cows to accompany him. In the screenshot further down you can see what that building looks like ingame; it's basically large log walls with corpses on pikes throughout.
The Fortress that the Cow King is in looks like this on the map.
What this level is good for is insane mob density; If you are looking to farm Champ/Boss packs there will definitely be better areas for you to go. The cows in this level aren't immune to anything, even on Hell difficulty. Only Champ/Boss packs will have any immunities throughout this zone.
Even though they have no immunities the cows throughout this zone are still very difficult. They have some of the highest hit points in the game for regular monsters and they also hit very hard and very fast. It's easy to get surrounded and overwhelmed while fighting them if you're a melee character. Casters will have to worry about getting three to four shot or locked in an endless chain of hit recoveries if you lack FHR since they hit so hard.
I would highly recommend that you do not use /players 8 when hunting in The Secret Cow Level as it gives the cows an insane amount of HP. Try /players 5 or even /players 3 if you find 5 to be too challenging. If you're still able to obtain a fast clear speed with it set to /players 8 then more power to you but I doubt many classes are capable of that.
The Red Portal that drops you into the Cow Level is usually not safe either. Depending on your strategy you'll either want to drag the enemies away from the red portal early on incase you die or make sure you clear around it before moving on incase you have to come back naked.
All of the cows in this level have a very far agro radius and move extremely slow, this makes it easy to do what's referred to as 'herding'. This is where you run around parts of the map and pull a bunch of cows into a small pile which you then AoE down more easily.
Herding cows together works very well for characters with AoE abilities.
Complete map of The Secret Cow Level on Hell difficulty.
There are a few other quirks that the Secret Cow Level has, first one being that Cow King's Leathers is a unique set item that can only drop in this zone. It's a low level set of armor that is mostly good for twinking out noobie characters if you have nothing better.