Conflicting reports on drop rates for mythics. Some saying 1% some 1.5%, and some even saying 2%. Some claiming higher percentages for Duriel and Andariel.
Many posters are complaining about not finding mythics after 100s of runs.
I’ve had quite a few, around 8. I’ve likely done in the region of 100 to 200 boss runs. However, each run results in several unique drops, perhaps as many as 5 (torment tier dependent I presume). So we need to understand if the rate is per batch or per drop. Makes a huge difference when calculating the probability (number of trials).
Assuming 1% across the board per drop and 5 drops per run, using binomials, here are the rates for at least k successes over 100 boss runs (i.e. 500 trials):
At least 1 mythic: 99.34%
At least 2 mythic: 96.02%
At least 3 mythic: 87.66%
At least 4 mythic: 73.64%
At least 5 mythic: 56.04%
…
At least 10 mythic: 3.11%
If you do the binomial calc yourself, since the trials are high, cancel out the factorials using the denominator, otherwise you’ll overflow too easily. Easiest approach is use Excel (built in binomial function) or a library for your fav. language.
In my case the trials would be 500 to 1000, which yields in the region of 14% to 78% chance of 8 or more mythics. So doable.
I had a mythic drop from the Curiosity vendor (Obols)!
Good luck with the farming!
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Twice this week I killed Varshan and Grig enough times to get 50 eggs and 50 shards. Then I went and did 25 Duriel rotations (100 kills).
So that’s roughly 300 boss kills. Zero mythics.
Earlier this season I was getting them like crazy. Not sure if something’s changed or if I’m just unlucky this week.
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Meant to add, chance of getting nothing over n trials is (1 - p)^n (carat for exponential, since I’m not sure the forum supports superscript).
500 trials would yield a chance of nothing of 0.66% (which is what I’d expect since the chance of at least 1 is 99.34%).
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The drop rate chance is somewhere in the 2% range correct?
If so couldnt we simply say that in 100 runs you could expect to see 2 mythics? Of course this is nowhere near perfect but seems to fit. In about 125 runs I have gotten 2 mythics. Yea the drop rate stinks, its a ton of grinding. The other route with runes is not really much better. In all I wish the drop rate was a bit higher.
I got a total of three Mythics from latter bosses. (Solo) 1st shroud of false death. 2nd Doombringer
3rd Grandfather. All 1 GA. Not too bad, But nothing else so far.
So Ive done hundreds upon hundreds of runs and got around 25-30 mythics. Only 1 mythic had a GA over 1 out of all of them. And most of my drops were the Starless ring and the amulet. I did get others(helms, chest pieces, polearm) but i would say 75% of my drops are the damn ring or amulet.
i like the drop rate last season. this time is just nothing upon nothing.
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I have never gotten a mythic from Durial or Andariel in any season.
Only mythics I have gotten are from Varshan, Lord Zir, and Gregorie. And once in season 4 from a helltide chest.
But that’s how crazy RNG is. Was doing a set of Durial runs with friends, and one guy got 12 mythics. (Another got 4, another got 3, I got zero. 
)
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There will always be people who tell you it’s just RNG—myself included. 
I’m still at zero for the last three seasons. I still try and have done a great many Duriel/Anderiel runs but have gotten no Mythics.
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just for the record:
today did around 600+ steels ie 50+ rounds of Grigoire = Doombringer + Shroud.
I got a bunch of Mythics from all Torment tiers. Seems like T4 has a bigger dropping chance. Maybe because I’m focusing on T4 now.
All drops had been random only from all T Bosses. Zero from obols & Undercity.
i ran 8 boss kills on T2 today 3 (varshan) and 1 of each for the other bosses and Andariel dropped the spear for my druid. Before that i’ve probably done 50 kills spread over all the bosses and all on T2.
Why even farm them? They will be changed again. For the 5th time in a row?
Because you become a God for the rest of the season 
Well, at least for the SB. The Shroud of False Death Mythic is just so cool.
Which Torment level you are playing? You only get a consistent drop at T4.
Tribute of Ascendance. Best chances for a mythic or 2.
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Tormented bosses on T4 will drop them eventually. RNG is RNG. Boss mats are plentiful this season, so summoning them isn’t as much of an issue as it was in the past.
The tribute of ascendance on T4 has the highest drop rate for mythics in the game by far (with chances for multiple mythic drops), assuming that it’s not bugged when you clear it and actually get the guaranteed uniques at the end. The last one I cleared didn’t drop a single unique, so in some cases it’s still bugged.
I would save those tributes until Blizzard actually fixes undercity.
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Supposedly those numbers are correct. I did 575 runs of Duriel. Only 1 mythic. Not a single item with more than 1 ga. I’ve done 1000s of boss runs in S6. With only 3 mythic and 1 2ga unique to show for it. This season is god awful for getting any decent unique/mythic gear. Thank god Blizz messed up the SB just as badly they did drops. We don’t need good gear.
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Wow… Seriously? 1 in 575?
In my case, I started to suspect that every 50/50 stack of Duriel materials would generate 1 mythic. So far, I’ve experienced 3 rounds of 50/50, meaning that about every 25 runs, 1 mythic drops. This is on world tier 4.