Talk:Armor penetration/@comment-3529242-20121030000306/@comment-1994689-20121030085912

I'd prefer to think that 1 APen decreases the EHP of all my targets by 1%

1APen = -1% EHP

While 1 point of Armour Reduction on an enemy decreases only their EHP by 1% but against all sources.

1ARed = -1% EHP

I hope that makes sense, it's simply the inverse of having armour. If you really want a formula to show the % damage increase then here you go (you'll probably get headaches again).

% Damage increase = 100/100/(100+[Target's armour])-100/(100+([Target's armour]-[Flat Reduction])*[% Reduction]*[% Penetration]-[Flat Penetration]))

So you can see why it's better from the other perspective right? You can't get a more concise formula because %damage increase per point of armour penetration will change depending on the target's armour like you said.