They should just give DRKs Bloodbath. It works amazingly well on Reaper especially when shit hits the fan on big pulls in dungeons(even at lvl 90) where the big potencies and percentage heals can save the group if you have a decent healer. Especially during Enshroud phases and the small HoT from Crest.

DRKs sustain problems wouldn't be an issue if Abyssal Drain was reverted to it's Stormblood incarnation and used MP instead of being tied to recast.

It's ridiculous how PLD/WAR/GNB have great sustain options but DRK has very little.