| Break |
Break is a keyword action.
If there is no creature with the Blocker keyword to stop the attack, one of your opponent's shields is broken. That means you get to choose one of those shields and your opponent puts it into his/her hand (unless an effect like Bolmeteus Steel Dragon's says otherwise). It also enables the opponent to use cards with the Shield Trigger ability, so attacking recklessly may cause ambush and reversal.