Burst Mode is an ability unique to Dark Marshal and his followers, during this he can rise his power levels to tremendous levels, between 400-1200% of the original level. Investigations have shown this is similar to the biotical overtaking Harbinger performs on the Collectors. Scientists are now theorising that it might have the same basis, and Dark Marshal might be able to take over his followers, or at least empower them.
Once the Burst Mode is achieved, the person's skin cracks open in places and underneath it originates a strange light, with the colour of molten rock. Then a strangly red and black aura starts to be emitted from the body, and the eyes begin to glow in a dangerous and frightning yellow. The "host" now has more endurance,strenght,speed, his far more intelligent etc. Yet, as most of them are not originally destined to achieve the Burst Mode, or they are ebing used to soon, the moment the Burst Mode is released, or the person dies. Spontanious Combastion happens, burning the body and all evidence with it.
Later on, it was discovered that indeed the mirrior elemental power is the origin of this power and that all generels within the army of the Dark Masters have their own and unqiue Burst Mode, resulting in a different form, and often huge changes in bodystructure.