I'm rusty as hell with Ragna so there may be better ways to do this, but I modified your challenge combo slightly so that it didn't require a raw OD activation and was hit-confirmable off the FC scythe. It's literally the exact same combo except you replace the DS DC > 5D with something else. It's obviously not as potent, but again - no yolo OD activation.
214D, land, 66, OD, 5B, 5D, Delayed Carnage Scissors, 623D, j236C, j214D, Falling jD, j214B, j214D, Jump Cancel, jD, j214D, 214214D
Damage: 6234
Lifesteal: 4000-4500 (Just did the challenge mode and it fell in between there)
Obviously requires 100% heat but may not need the maximum OD duration, didn't try it with more HP.
Only tried it against Azrael and Noel. Both worked, but Noel requires a much cleaner dash and OD cancel to not have the 5D whiff.
There's probably a much better way to go after seeing a fatal counter scythe land in the corner, but I'm not creative and just jacked your combo.
EDIT: http://www.youtube.com/watch?feature=player_detailpage&v=16ZYpteDn6s#t=146
1:46ish in that video is another option. No idea how difficult or practical it is in comparison. Also that DS would whiff in the corner until the next patch.
