Let's do some math guys

Initial conditions:
Single Player
Location: K3K B.A.
Magic Find: 100
Players Count: 1
Chance to drop Ancient Armor base:
BaseChance = (420 / 1701) * (2 / 438) * (3 / 60) = 1 / 17739
Chance to drop a Unique:
InitChance = (BaseChance - (ilvl - qlvl) / Divisor) * 128 = (170 - (115 - 90) / 1) * 128 = 18560
EffectiveMF = MF * Factor / (MF + Factor) = 100 * 250 / (100 + 250) = 71
Chance = InitChance * 100 / (100 + EffectiveMF) = 18560 * 100 / (100 + 71) = 10853
ModChance = (Chance < MinChance) ? MinChance : Chance = (10853 < 3500) ? 3500 : 10853 = 10853
FinalChance = ModChance - (ModChance * QualityFactor / 1024) = { QualityFactor = 0 } = 10853
Chance to drop a Set:
InitChance = (BaseChance - (ilvl - qlvl) / Divisor) * 128 = (25 - (115 - 90) / 5) * 128 = 2560
EffectiveMF = MF * Factor / (MF + Factor) = 100 * 500 / (100 + 500) = 83
Chance = InitChance * 100 / (100 + EffectiveMF) = 2560 * 100 / (100 + 83) = 1398
ModChance = (Chance < MinChance) ? MinChance : Chance = (1398 < 640) ? 640 : 1398 = 1398
FinalChance = ModChance - (ModChance * QualityFactor / 1024) = 1398 - (1398 * 556 / 1024) = 638
Real chance to drop a Set piece:
RealChance = (1 - 1 / (UniqueChance / 128)) * 1 / (SetChance / 128) = (1 - (128 / 10853)) * (128 / 638) = 62400 / 314737
Chance to drop Set Ancient Armor:
TotalChance = BaseChance * RealChance = (1 / 17739) * (62400 / 314737) = 20800 / 1861039881
And finally chance to become:
Avalanche
Avalanche
Ancient Armor (Sacred)
Defense: 9489 to 11748
Required Level: 90
Required Strength: 770
Item Level: 1
+(1 to 2) to Barbarian Skill Levels
20% Movement Speed
Stun Attack
+200% Enhanced Defense
+(41 to 50) to Vitality
(11 to 15)% Bonus to Defense
Socketed (6)
Mount Arreat
(Barbarian Earthshaker Set)
= (1 / 5) * (20800 / 1861039881) = ~2.235 * 10^-6
(1 per 450k skeletons on average)Cinadide's Forge
= (2 / 5) * (20800 / 1861039881) = ~4.471 * 10^-6
(1 per 225k skeletons on average)Rathma's Skeleton
Rathma's Skeleton
Ancient Armor (Sacred)
Defense: (6326 - 7907) to (7832 - 9790)
Required Level: 90
Required Strength: 616
Item Level: 1
+(1 to 2) to Necromancer Skill Levels
40% Hit Recovery
+(100 to 150)% Enhanced Defense
Lightning Resist +(31 to 50)%
Physical Resist 5%
Requirements -20%
Socketed (6)
Rathma's Empire
(Necromancer Melee Set)
= (2 / 5) * (20800 / 1861039881) = ~4.471 * 10^-6
(1 per 225k skeletons on average)So now you can start bitching, I did the math for you
Anyways, gist of that story is quite simple: numbers are useless if you don't understand them. I was always bad at math, probability theory and mathematical statistics yet I can use it and make some conclusions. And the conclusion is
1 per 225k on average doesn't mean
1 every 225k, if you can't comprehend it don't even bother to start your theorycrafting.
Edit: Fixed unique & set chance calculation, there is no floating point arithmetic involved into it, though this results are still an approximation.