The power to let loose an explosion from their body and potentially recover afterward.
The user builds up immense energy and pressure within his body, and then literally causes themselves to explode. One with this ability usually can vary the power of the explosion after some practice; from simply blowing open a door to nuclear and atomic explosions.
Some can simply blow up portions of their body, like their fist or their leg, and then reassembling them afterwards. If the person uses their fist or leg as a attack and then blowing up said body part upon contact will give their enemy a explosive attack..
Some have their body become vapors as they explode, then reform. Others have their body fall apart, where their body recollects itself. It is also possible to use this as a last-ditch attempt, where they will die after that, but collect energy and pressure like other users.