We have recently discussed the D-Reaper engine, and while for the most parts he appears an interesting concept, the engine itself has a large shortcoming.
The deck relies too much on summoning one D-Reaper and it’s consecutive attacks.
Specifically, much resources will be placed in preparing Mother D-Reaper’s 7 digivolution cards during the early game, and when that timer hits, D-Reaper can be played for free and begins consecutively swinging at your opponent’s security. It would be ideal (and mostly essential) to be able to end the game then, as losing that D-Reaper would usually mean that you will have to restart the system and rebuild your Mother’s digivolution again.