1.13 Hell Countess Runes... again... again [special drop rates] de

[NOLAFatCat]

I was on the slashdiablo servers talking with the admins about drop rates on the countess when we realized no one had an answer about the 1.13 patch.
I/we understand the drop rates for runes in her normal drop slots have been increased like everyone else in the 1.13 patch; has her special drop rates been increased as well?

[Krupa]

iīm not an expert, but here is how i understood the process, without doing too much research

if a monster "chooses" to drop a rune, the highest possible rune class is chosen and checked if it is dropped. if that one is not chosen then the same things starts with the next lower rune class and checks again if this one is chosen. if not, than the next lower rune class...

the special rune drop of the countess should work after the same principle, just that runes donīt have to be chosen, but are the only type of item that can drop.
higher player settings will overwrite the special drop with a normal drop.

so if i understood it correctly the increase of probability to drop a rune increased the chances of dropping higher runes and lowered the amount of the lower ones with her special drop (and also all other drops too). but the highest possible rune from her special drop did not change

[Victus]

Runes are grouped in classes as Krupa said (Runes 1 for El and Eld, Runes 2 for Tir and Nef and so on up to Runes 17 with contains Zod alone). The change that 1.13c brings is to rebalance the odds by putting more weight to higher runes. That has global effect in the game without changing the overall amount of rune drops. You just get more higher instead lower runes.
Now about The Countess - her own TC is divided in two separate TC: Countess Item and Countess Rune. First she makes 5 picks from Countess Item TC and after that 3 more picks from Countess Rune TC (remember that monsters are capped at maximum of six drops). Her item TC can drop runes too (up to Runes14 in hell) but with much lower probability than her rune TC (up to Rune12 in hell). So in order to maximize her rune drops you need less items from item TC which means high nodrop which means players1.
Short answer to OP - her special rune TC is the same but the drop rate for its higher runes is increased.

[Korlic]

I was wondering if there is any way of knowing the likelyhood of the countess dropping specific runes on average at players1? E.g how many runs (on avg.) to get FAL, LEM or some other specific rune.

[Victus]

You can calculate the probability for specific rune drop(s) from n runs. It's called Bernoulli scheme:
P(n,k)=n!/(k!(n-k)!)*p^k*q^(n-k), where
p - probability for specific rune to drop in one kill (for v1.13 can be found here)
q=1-p - the probability to not drop that rune in one kill
n - the number of runs
k - the exact number of runes dropped

But I guess that you are interested in the case where at least one rune drops which is:
P(n,k>=1)= 1-P(n,k=0)= 1-q^n

[Korlic]

Thx! That calc was exactly what I needed

Funny thing, in open play (No countess or forge) I have found only Lem as a midlvl rune. But no less than four high runes. 2 x Gul, Cham and Ohm. No Um, Pul, Fal, Ko. Im NOT complaining, just think its really weird. Did the change in rune drops, make mid runes drop way less, or is it just a coincidence?

[Victus]

Runes El-Nef drop less in 1.13 compared to pre1.13, Eth-Ith pretty much the same and all other runes are more common in 1.13. Additionally the difference in probability between mid and high runes is much lower in 1.13 than 1.12. For example Cham is 5.4 times rarer than Um in 1.13 but 16.4 times rarer in 1.12.

[Korlic]

Wow thats a big difference! How about in 1.10? Thats what I played the most.

[Victus]

Versions 1.10 to 1.12 have identical drops.