My best monster drop would be a Mal from an oblivion knight in nightmare Chaos Sanctuary (just checked ATMA... one in 1.25 million :crazyeyes, and an Um, Pul, Lem, and everything below that from Countess. From the forge I've gotten a Mal and a Pul.
2*Sur ~2years apart. The first one was dropped by some random zombie when I was on my way to kill hell Andy. The second one dropped in CS but I didn't see which monster dropped it.
iv never got a hr.. but iv had so many lower runes.. ists and such, iv had about 4 ists from countess this ladder, 2 ists from popping the courpses at andy, a mal from pits in a full baal game, and a gul from wsk, and plenty of other runes in the past.. but no hr ever
not that im bothered as iv had a few hrs in rune drops... and loads of hr's in item drops
i play single player and was SHOCKED when i found a cham rune in the 2nd level of the stony tomb. one of the lightning beetles in the same room as creeping feature dropped it. then right after that i found a mal rune from one of shenks minions! those were the first high runes ive ever found too!
Some months ago I found a Sur in sp in the Cow Level, yeah pot luck. Recently I got Gul from hellforge drop, but I guess it doesn´t count, since it´s easier to get a Gul from hellforge than from monsters.