Armour applies to Elemental DMG vs Pyromantic Pact - does it work?

Pyromantic Pact - "When you reach max Infernal Flame, your Infernal Flame is set to 0, but you take fire damage equal to your maximum Life and Energy Shield. This damage counts as a Hit, but it cannot Stun."

Armour applies to Elemental DMG - clearly it should mitigate hit dmg from elemental hit, and since pyromantic Pact damage counts as hit, in theory it should mitigate it.

But apparently it doesn't?!

I have 144% of armour Applying to fire damage + 75% Fire resistance and if I'm taking armour conversion off - I still do receive same amount of dmg on a Pact trigger. So do I understand something wrong way, or it's simply a bug??

Anyone knows anything about it?
HALP!

I have the same thought as well since I recently noticed that my remaining HP percentage after Pact reset was roughly 25% the same (75% Fire Resistance) either I had 0% or 65% of armor applies to elemental damage. My in game said estimate elemental damage reduction is 47%.

Not sure that it doesn't work only for this skill or misunderstand anything. I believed that this skill still work on enemy hit.

Hope someone can clarify this. In 0.4, I invested this with the expectation that it work to mitigate Pact damage ^^".

It should work in theory.

Damage reduction = armour/(armour +10xdamage))

Forget the percentage estimates the game gives you for armour damage reductions, these are based off of average white mobs hits.

If a hit is for 1% of your armour total you get 90% damage reduction.
10% of your armour total gives 50% damage reduction.
20% of your armour gives 33% damage reduction.
30% of your armour gives 25% damage reduction.
etc.

My guess is that the combined total of life and energy shield is just too high a percentage of your armour vs fire to be giving you much in the way of damage reduction from the armour.

Thank you for the clarification which enlightened me. I'm clear now, with the given formula (not by in game reduction %). The damage from HP+ES are big and almost the same to armor apply to element resist which resulted in almost no impact to the final damage reduction.

Given my HP+ES = 5000, my Armor apply to elemental damage is 3400 and 75% Fire resistance:
-> If only fire resistance applied => 5000*(1-0.75) = 1250 received damage
-> If fire resistance and armor applied => 5200*(1-(3400/(3400+5200*10)))*(1-0.75) = 1220 => 1220 of 5000 => 24.4% received damage (75.6% damage reduction)