One thing I have to admit was overpowered on doom crab is that even when a person puts down a shield the doomball will still apply its AOE when it hits. So my suggestion is to just have the shield delete the doomball outright so that doesn't even apply it. essentially make it so the shield actually blocks the AOE as well as the projectile itself. This is the only real thing that I can think of having mained it as a boss. the projectile itself is pretty balanced as things like doorways completely destroy it. It has a funny hitbox that strangely enough makes it pretty balanced. I just really wanna be able to play doomcrab again.