A member of the Mutant Liberation Front, Reaper is best known for killing people with his weapon that resembles the one that the Grim Reaper wields. Reaper uses this weapon often to behead people, while his mutant powers of synaptic neural channeling disables his opponents..
Shatterstar has faced this enemy at least twice while on X-Force: once in X-Force #1 and once in X-Force #27. The results from both situations proved similar. In X-Force #1, Shatterstar dismembers Reaper's left hand, but does not kill Reaper. In X-Force #27-28, X-Force again clashes with the Mutant Liberation Front, and Shatterstar once again is pitted against Reaper. In this occasion, Shatterstar dismembers Reaper's right hand. Facing certain defeat, Reaper was helped out by teammate Wildside, who had Siryn held captive. Wildside forced Shatterstar to drop his sword. Wildside gets Shatterstar's sword, but little did he know, Shatterstar was using his mutant ability to resonate a shockwave through his blade. Before he knew it, the blade discharged and seemingly injures Reaper severely, while Shatterstar takes down Wildside.
Currently, Reaper is still alive (his hand was reattached by Reignfire during the reformation of the MLF) and currently still plays a role with Malibu's All New Exiles.
Information about Reaper provided by John Dilthey. Thanks a million, John!