Break Out! is an element that appears commonly throughout the Dept. Heaven series. The context of this term is dynamic and depends largely on the title in question, but a Break Out! is essentially a special move.
Break Outs first appeared in Riviera: The Promised Land. When a player character uses an Over Skill of Lv. 1 or Lv. 2, it is considered a Break Out!. For enemies such as demons, Break Out! is their ultimate move, triggered when their Rage Meter hits its peak. This variation is more-or-less the demons' equivalent to a Lv. 3 Over Skill. Each class of demon has its own Break Out!, each with unique properties. All non-generic bosses have unique Break Out! skills.
Returning in Yggdra Union, each Card Skill activation is considered a Break Out!.
Break Out! returns once more in Gungnir. When any unit on the field uses a skill of any kind, it is considered a Break Out!, subverting the significance of the term into something less special.