[Billy] Paintball Round

When Billy activates Quick Assist/EX Special Attack/Chain Attack/Ultimate, he gains 1/2/2/4 stacks of Charge, stacking up to 4 times. When Billy performs a piercing attack in a large area around him during Dash Attack: Starlight Sanction, press Basic Attack to consume 1 stack of Charge and trigger the skill repeatedly. Upon hit the enemy's DEF is reduced by 4% for 12s, stacking up to 12 times, and repeated triggers reset the duration.