Pierce X
When a unit attacks with an Attack Pool that has Pierce X keyword it may cancel up to X block results during the Modify Defense Dice step.
The Pierce X keyword can be used to cancel block results on defense dice rolled by a unit using the Guardian X keyword. When doing so, treat canceled block results as Blank results. After using the Pierce X keyword in this way, any unused Pierce X value can still be used to cancel block results rolled by the defending unit.
For example, a unit with Pierce 3 attacks an enemy unit, and another enemy unit uses Guardian 2 to cancel 2 hit results. After converting defense def. surge results, the unit using Guardian has rolled 2 block results. The attacking unit uses Pierce to cancel the 2 block results and the unit using Guardian suffers 2 Wounds.
Now the defending unit rolls defense dice and the attacking unit may cancel 1 more block result rolled by the defending unit since only 2 of its original Pierce 3 have been used so far.