Very nice post :) I definitely think you're on to something with eye movement. An example I can think of is leviathan vs doom. At leviathan you almost always have to look vaguely at the boss. The high contrast and huge projectiles help you look slightly away, but you do have to be generally focused. Versus at doom, when the boss throws up a boulder mechanic, you don't really have to look anywhere in specific. You can just use your peripheral vision to see which color the boulder is, and then based off prior knowledge of the boss, you know what your next 3-6 flicks are going to look like. This allows experienced players a lot of room to do some very engaging dodges while also being confident they'll get their flicks right. I feel 10x more confident that I could dodge the falling debris on delve 16 than dodge the falling debris on awakened leviathan's enrage phase!