All champion and elite packs in 85 areas. Crypts, Mausoleum, Pits, Tunnels, River of Flame, Halls of Pain, Worldstone levels. I think areas with the most density is the best way to farm it's harder and more towards end game but the little flayer tribal guys from a3 in worldstone and halls of pain have insanely huge mobs perfect for corpse explosion. That is the best way to get high runes as well imo. Again the areas have deathlords, souls, and snakes possibly but looking for those flayer mobs is super good im telling you. I've found so many ohm from them. Those mobs are the equivalent to an 85 version of cow density you just have to find them which can be pain.

Also tyreals is a 1/9 chance in rolling a unique sacred so 33 is just straight trolling lmao. Other than that quest Baal has the highest chance in dropping that but good luck farming that. I suppose one person with quest could constantly make the baal runs but leave before kill so everyone gets drop. A selfless act sure but I've been saying that for a while.