This is mainly focused towards a PvE buff/tuning. Crust crusher is already a very risky ability that doesn't get used often during a fight so having it up more often wouldn't change anything about it in PvP. Backflow at best would allow you to do a super armor trade more often but the damage from the ability and the protection time you gain from it both aren't high enough to impact anything too much. The point of reducing the CD's is that Musa's combo's are all terrible flow wise. You rotate through your main awakening combo and then your damage immediately drops as you're either using the low damage fillers or just holding down crosscut until one of your main abilities come back up. You move from pack to pack and you often find that Backflow still isn't up for several seconds even after finishing a pack and finishing your rotation on the new one. With crust crusher you'll be using it once every several packs in lower tier areas down to every other pack in a place like Aakman. If Musa capping out efficiency wise at Aakman but still losing out to Archer is fine then surely it wouldn't be a massive problem to give him a small buff like this. Lowering Backflow to be in line with the rest of his CD's (9-10 seconds) and then putting crust crusher slightly above that would be fine.