An apparatus for activating a wellbore tool may include a first sub, gas transfer sub, and a second sub. The first sub has an igniter that generates a flame output that ignites a power charge. The power charge generates a high pressure gas when ignited by the flame output. The gas transfer sub has a first end receiving a portion of the power charge, a longitudinal bore, and a plurality of flow passages radiating from the longitudinal bore. The flow passages provide fluid communication between the longitudinal bore and the first sub. The second sub includes a shaft having a first end connectable with the gas transfer sub.