Penetrating Strike (Mythic)
You know just how to strike to bypass even the most heavily armored foe’s defenses.
Prerequisite: Penetrating Strike.
Benefit: When using Penetrating Strike or Greater Penetrating Strike, you can ignore an additional point of damage reduction for every 3 tiers you posses. Additionally, the effects apply to damage reduction without a type (such as DR 10/—).
Source: Mythic Adventures, p. 70