A system and method for making and using a multi-point initiation explosive device that produces an enhanced pressure wave for severing tubing, pipe or casing in an oil or gas well. At least two opposed initiators initiate a column of explosive material from opposite ends, thereby generating opposing pressure waves propagating toward a midpoint between the initial initiators. A shaped-charge assembly with a liner located at the midpoint initiates immediately prior to the arrival of the opposing pressure waves and forms a fast moving jet to pre-score the target pipe prior to the arrival of the pressure pulse propagating from the initial detonations.