Breaker

Breaker is generic name of keywords that have "breaker" in their names.

Details
There are 8 different breaker keywords. This includes;
 * Double Breaker
 * Triple Breaker
 * Quattro Breaker
 * Crew Breaker
 * World Breaker
 * Civilization Breaker
 * Galaxy Breaker
 * Infinity Breaker

Normally when one of your creatures attack your opponent and are unblocked, they break a single shield. Each of these keywords allow your creatures to break additional shields.

Rulings

 * If a creature has multiple breaker abilities such as Double Breaker and Triple Breaker, only the breaker ability that breaks the highest amount of shields (in this example; Triple Breaker is 3) is the ability that applies when shields are broken.