Talk:Armor/@comment-89.156.3.186-20121220152350/@comment-4087140-20121220190044

"True damage on effective health" is always equal to the base damage. If you have armor penetration, then you treat the target as having less effective health. For example:
 * Target A has 1000 health and 100 armor: 2000 effective health. You have an attack that deals 200 physical damage.  You deal 200 damage to their effective health, or 10% of their total health.  Thus, their actual health is reduced by 100 (10% of their maximum actual health).
 * Target B has 1000 health and 100 armor, but you have 100 armor penetration: 1000 effective health. You have an attack that deals 200 physical damage.  You deal 200 damage to their effective health, or 20% of their total health.  Thus, their actual health is reduced by 200 (20% of their maximum actual health).

Penetration doesn't change anything on the attacking end, it changes the defending end; a part of the target's armor is ignored.