Mileena performing a Breaker against Kenshi
Breaker is a unique function first introduced in Mortal Kombat: Deception. It allowed the user to break and interrupt the attacker's combo while it was being performed. By holding the Block button while holding Forward, the defender immediately stops the combo and knocks them back though this does not damage them. Breakers could only be used three times per match. Possibility of a Breaker is indicated by the blue marker lighting up beneath the health gauge.
Breakers returned in Mortal Kombat: Armageddon and Mortal Kombat vs. DC Universe in which in the former, Aerial Breakers could be performed due to the inclusion of Aerial Kombat.
In MK vs. DCU, the Rage meter is broken up into halves with Breakers using one half of the meter to perform. In Mortal Kombat (2011) as well as Mortal Kombat X, the meter is composed of thirds, with a Breaker requiring two thirds of a full bar to perform. Thus decreasing the limit in which they can be done in those games.
Breakers were created when players could perform sequences of uninterruptable combos in the earlier games. As a result, Breakers were added to minimize the damage.
The effectiveness of the Breaker is debatable. While they may save the user from very damaging combos, they share the same power up bars as other unbreakable attacks like Rage from MK vs. DCU or X-Ray Attacks in Mortal Kombat (2011).