The Power Badge allows you to gain bonuses when you play a power card (denoted by the symbol in the bottom-left corner). Some cards also only activate their effects if you have the Power Badge. You can earn a Power Badge by choosing Strongharm as your class, or by investing skill points in the Badge as another class.
Rank 1: 50% chance to gain +1 shield
Rank 2: +1 shield
Rank 3: +1 shield 20% chance to gain an additional shield
Rank 4: 1+ shield 40% chance to gain an additional shield
Rank 5: ?