An explanation of the strategy for the Archangel Crabaddon boss fight.
When it opens a claw, shoot an arrow into it. (If you don't, it shoots out bubbles that you can pop to get more arrows.) If it shakes its head from side to side, it will dash downward, so don't be in front of it. When it opens its mouth, shoot an arrow into it.
If Crabaddon is the boss of the fourth dungeon or later, there will be a second phase of the battle. In the second phase, if the mask shakes, it will dash forward, so don't be in front of it. It has two spinning masks. When the mask's teeth turn into an eye, shoot the eye. Do the same with the other mask. The mask will then have a black cloud in its mouth, and then will shoot water out. Shoot the black cloud before it spits out the water.