The Glumstone Effect.
*clears throat*
There is a recurring problem in Cuphead game design, which only a few bosses have been able to escape. I have decided to name that problem "The Glumstone Effect". The Glumstone Effect means that the boss is basically a wall that fires projectiles. See, this is a problem, because fighting a dynamic enemy is generally much more interesting than fighting a wall. The name is coined after the first phase of Gnome Way Out, where Glumstone The Giant perfectly demonstrates this effect. In the intro animation, he's literally a rocky mountain, or a wall, and during the fight, Glumstone is so stationary that his beard is a part of the landscape.
See extra:
The King's Leap mostly does a pretty good job of subverting the Glumstone Effect, except for the end, where MDHR got lazy and created the Rook. However, of all the bosses in the entire game of Cuphead, one of them does the best job of throwing the Glumstone effect in the trash and setting it on fire.
That boss is The Knight, with their sophisticated, medium-paced fencing match of a bossfight.
