In classic Diablo 2 games, if The Cow King was killed by any member of your party (I’m almost certain it’s “any member of your party” and not by anyone in the entire level, but I could be wrong), all members of that party could not make a Secret Cow Level on that difficulty again even if they had no hand in actually killing The Cow King. However, I recently learned that this is not the case in Diablo 2: Resurrected, and you can kill The Cow King as many times as you would like — on purpose, by accident, whatever — and it does not affect your ability to make subsequent games. Now you don’t have to worry about someone who didn’t know killing him and screwing up your ability to make Secret Cow Levels on that difficulties in the future, and if someone wants to kill him (or more than one person), they are absolutely free to do so without repercussion. So far, I’ve been mining Normal and Nightmare Cow Levels on our sorceress because she can easily, effortlessly kill cows by herself on those difficulties, and I’ve gotten three Runes and two set pieces for my “troubles” so far, and that’s just with me having enough Magic Find gear on our sorceress to make it worthwhile… for the most part. I’m mainly doing it to farm runes, so any additional set pieces that I get that I don’t need will quite likely be given to my friends, people new to the game, or both of those things. Sweet!

So far I’ve gotten two runes and two set items off of soloing Normal and Nightmare Cow levels.