

I got most of my high runes by doing just that and they were usually dropped by random bosses not Countess or Diablo or even Baal although Baal dropped me few ber and Lo runes. From stony field and tower in black marsh go to tal rasha thumbs in act 2 to lower kurast and travincal in act 3 to Chaos Sanctuary in act 4 and to killing baal in act 5. Best way to do it is to pick 10 locations on Hell Level and run through all of them in the same game: pick your own 10 high concentration areas in different acts and run all of them by going from one act to the other, one location to the other, all in a single game.

Understand that sometimes 500 runs is required to get a top tier drop. Farming one spot like Travincal or achaos Sanctuary can work but many give up farming the same place if they don't get high run in the first 100 runs.

You just have to keep killing thousands of monsters on Hell level and these runes will drop finally. Getting the highest level rune is a one in a hundreds of thousands chance. Chaos Sanctuary is a good place: lots of bosses and monster in a relatively small area but so are all pits, wholes, dungeons and so on and so forth. The other bonus is that the Countess has a unique secondary loot table for dropping a wide range of runes. What worked the best for me was simply going back to all the very high monster concentration spots and just kill everything. The Hell Countess is one of the 3 mini bosses in Diablo 2 Resurrected that drops keys needed to summon the Uber Tristram Portals. The truth is, on Battlenet, despite what many people think, farming one particular spot is a waste of time. First, we are talking Hell level only as you have the highest chance of getting high runes there.
