Still new to the Rune farming...where do you get....

Ko, Fal, Lo, Lum

Seems those are standard (mid it seems?) runes for many trades. Exclusing the Pul and whatever above.

I have a 50 amazon, which stopped playing while focusing on lvl'ing other characters. She's just starting A3 NM and haven't continued since.

I assume they drop regularly from countess on H?

Lum and Ko drop from countess. You get some Fals too. But honestly there's probably better places for rune farming than countess. Hell cows for example are great if you have a javazon. Lo? Good luck with that from The Countess, unless some of the wraiths in the tower drop it you cannot get that rune there. You possibly meant Io. Best places for rune farming on Bnet are possibly Hell cows, Travincal, and Chaos Sanc (+every other lv85 area). Rune drops are rare that is why they are used as currency.

Ko, Fal and Lum are Mid-Runes, yes. You can find them farming NM and Hell Countess and Hell in general. Hell Cows is also a good area.
If you really mean a Lo rune, thats a High Rune (HR) and drops pretty rarely and not from Countess.
Lower Kurast runs are a good way for HR searching.
As a rule of thumb for runes in general:
Kill as many Hell Monsters as possible. Magic Find doesn't affect rune drops.

https://d2.maxroll.gg/d2-drop-calculator is a great resource for drop information. You can choose a type of enemy to see everything they can drop & what the chance is it will drop from them, or choose an item & see a list of what enemies can drop it & their chances to drop it.

Drop calculators are good for individual items but not really for runes @EnragedN3wb. For HR farming the important thing is to kill many monsters, rather than the right monsters. While I agree that the chances of dropping an HR from a single mob are higher as the calculator says here's an example. According to it, Rakanishu has twice as high of a chance to drop an Ist rune compared to a boss champion cow. Not sure how many Ists you have seen from Raka compared to cows but I'd venture and guess cows have netted you more Ists . This is simply because of the high monster density in the cow level. Sure, chances are not really big but there's hundreds of them so you're probably statistically more likely to get an Ist rune in fewer runs from cows compared to The Countess (the single monster with highest drop chance for an Ist).

For HR farming the important thing is to kill many monsters, rather than the right monsters.

Oh I'm well aware, & completely agree. I've gotten more good runes from normal chests than anything else. I'd even go a step further & say your probably better off opening every chest on the way to a boss than actually killing the boss, as there are easily 20x more chests per run than bosses, so the boss would have to have over 20x the chance to drop w/e you're looking for to make skipping them worth it. I've found more SoJs from chests on the way to Andy, than Andy herself by a long shot

That said, it's still plenty useful to show which runes countess has a higher chance of dropping, which includes almost everything on their list(everything if they meant Io).

Thanks everyone for the replies.

In summary, I should continue with my 50 amazon , eventually Countess H runs and when I'm done with H, do cows.

i can just give you Ko and Lum, good luck on Lo tho

I think the drop rate is so low in general that only Blizzard could collect enough information to be statistically accurate. I have got 2 Vex runes total. Both off of non-boss devilkin in act one hell. My best ever is a Jah. It dropped in the Chaos Sanctuary. I don't know what monster dropped it, since I'm a necromancer and about 14 monsters exploded all at the same time.