(For author) - In addition to what I'd commented already in the video...a few more notes to add: my idea would be that to make this 'work' in a reliable manner you probably need to set the 'blockers' to the Icon up such that you (as the author) are able to determine precisely when all the blockers will move out of the way, how frequently it happens (i.e. amount of time between shooting opportunities), and for how long they stay out of the way (aiming for whatever your target is in both regards). Basically a repeating 'rhythm' or 'cycle' that you have figured out, per se. Otherwise it will likely remain unpredictable...and possible to find a 'cheese' opportunity for...also you might want to move the Icon further down in height IF you want it to need more than two hits (lowering the lift one time is sufficient to hit it twice, as I show).
Lastly...possibly don't just give out near infinte BFG only for the monsters that the boss will be spawning...but I need to see the finalization of the Icon mechanism itself to know that for sure...