Penetration subtracts from resistances, causing a source of damage to deal more damage.
Penetration applies after resistances are capped to 75%, and can reduce resistances to negative values.
For example, 30% lightning penetration against 20% lightning resistance will result in -10% lightning resistance.
All enemies gain 1% of penetration per area level, up to a maximum of 75%.
Players with less than 75% of each resistance at area level 75 and beyond will take increased damage due to having negative resistance values.
Enemies gain 1% penetration per area level, capped at 75% in areas level 75 and above. Overcapping resistances above 75% does not help mitigating this penetration.