Only usable while guarding. It interrupts your block to counterattack. It's fast and makes you temporarily invincible, so it's very useful for countering.
Can only be used when in blockstun. Basically a "counter" card, in which your character gains complete invincibility and counters with an attack that does no damage but knocks down your opponent on hit. The range of the counter hit is rather short, so this is mostly used when countering melee attacks to relieve pressure.