What's with the randomness, blizzard?

[MarcusSPB-21190]

I went to Elder Rift four times. Spent 40 legendary crests. Result: 4 stones with two stars, and 36 stones with one star. Where are the five star stones? 2/5, 3/5 (I don’t even dream about 4/5 and 5/5 anymore)

[RedOctober-12562]

Assuming all 40 Legendary Crests were the same type (Eternal Legendary, or non-Eternal Legendary), you stopped 10 short of the mercy drop. From what I’ve read in the past from posts you are supposed to get a 5* once per 50 Leg Crests. ETERNAL and NON-ETERNAL are not combined.

From the ER overview

• Odds of a 5* are 4.5% from each Leg Crests .
• For every 50 Legendary Crests used, you are guaranteed one 5-star Legendary Gem.
• The guarantee counter for Eternal Legendary Crests is separate from that of Legendary Crests.

[Meteorblade-2266]

@MarcusSPB-21190

Spent 40 legendary crests

Okay…

• Chance that a crest generates a 5-star gem = 4.5% = 0.045
• Chance that a crest does not generate a 5-star gem = 95.5% = 0.955
• Chance that none of X crests generate a 5-star gem = (0.955)^X

So…

• Chance that none of 40 crests generate a 5-star gem = (0.955)^40 = 0.15853854

So, roughly 16% of people would get this result, i.e. no 5-star gem from 40 crests.

Bad luck is not a bug.