The rules for Pierce state:
"An attack with the Pierce ability ignores 1 point of armor for each rank of Pierce it has. Thus, an attack with Pierce 3 ignores 3 points of armor. Shields are not affected by the Pierce ability."
This could be read one of two ways:
a) Pierce attacks subtract their pierce value from the target's armor value, then apply all the damage with the lower armor value.
b) Pierce attacks ignore the armor, and deal pierce damage up to the rank in Pierce, regardless of the target's armor value, and then apply the remaining damage modifed by armor, minus the ignored armor granted by Pierce.
Here are a few examples with each interpretation:
Damage Rolled: 5 (Pierce 2)
Target Armor: 3
Damage dealt: a) 4 , b) 4
Damage Rolled: 8 (Pierce 2)
Target Armor: 3
Damage dealt: a) 7 , b) 7
Damage Rolled: 3 (Pierce 2)
Target Armor: 3
Damage Dealt: a) 2 , b) 2
Damage Rolled: 2 (Pierce 2)
Target Armor: 5
Damage Dealt: a) 0 , b) 2
Damage Rolled: 3 (Pierce 4)
Target Armor: 5
Damage Dealt: a) 2 , b) 3
And for the *Coup-de-grace* attack situation:
Damage Rolled: 4 (Pierce 4)
Target Armor: 8
Damage Dealt: a) 0 , b) 4
As you can see, the interpretation makes a big difference against highly armored targets. Basically, since I am running with alot of skeletons with Pierce 2, regardless of the hero's armor value, our group interpretation "b" makes it so that I am assured that as long as I hit and get some hearts, at least 2 points of damage is going to go through.
What are your opinions/thoughts/<links to faq that clarify this>?