Armour Penetration Question

[Valilor]

I'm sorry if this has already been answered but I can't find it anywhere:

If a boss is fully sundered, they are down to 80% Armour - if you have 100% ArP (1400 approx) the boss has 0% armour. Is this correct?

If a boss is fully sundered to 80% and Faerie Fire goes up, dropping the armour by another 5%, what % ArP do we need to get to 0% armour on the boss? (Is F.Fire effectively a 5% ArP buff?)

If a boss has no sunder armour and we have 100% ArP - what happens? :S

[Raith]

I'm sorry if this has already been answered but I can't find it anywhere:

If a boss is fully sundered, they are down to 80% Armour - if you have 100% ArP (1400 approx) the boss has 0% armour. Is this correct?

If a boss is fully sundered to 80% and Faerie Fire goes up, dropping the armour by another 5%, what % ArP do we need to get to 0% armour on the boss? (Is F.Fire effectively a 5% ArP buff?)

If a boss has no sunder armour and we have 100% ArP - what happens? :S

ArP is calculated after sunder/faerie fire. It's best to explain it with examples.

Say a boss has 1000 armour, and you have 80% ArP. No sunder armour = 200 armour.

20% from sunder brings it down to 800, 80% ArP is then calculated and it has 100 armour.

100% ArP regardless of sunder/faerie fire means 0 armour.

EDIT: oh well, ignore that last part.

[Valilor]

Ah cool - so if you're hard capped, you don't need to worry about Sunder/FF being up or not. Cheers.

[LeperHerring]

100% ArP regardless of sunder/faerie fire means 0 armour.

No. You're correct that the personal armor reduction is calculated after FF/sunder. However, your personal armor reduction is calculated against the effective armor ( (armor after FF/sunder + 16635)/3 ) so in reality you can never reduce the armor to 0 even at 100% personal ArP. This is why FF/sun will help you even at 100% ArP.

[Nightsorrow]

No it does not make boss to have 0 armor ...

read here and learn

http://www.wowwiki.com/Armor_penetration

[Valilor]

No. You're correct that the personal armor reduction is calculated after FF/sunder. However, your personal armor reduction is calculated against the effective armor ( (armor after FF/sunder + 16635)/3 ) so in reality you can never reduce the armor to 0 even at 100% personal ArP. This is why FF/sun will help you even at 100% ArP.

Ok, let me get this straight.

A Boss has X amount of armour and Y amount of effective armour. X > Y and ArP can only apply to Y.

Y can get bigger if FF/Sunder is up but it will never equal X, therefore you will never take a boss to 0 Armour.

That sound about right?