Man, you went WAY WAY OVERBOARD with that final boss
That alone makes this level of Lunatic difficulty (at least for me). The idea is really cool, I'll grant you that... but it seems to me that it relies WAY too much on luck. Sometimes you can pass the first "form" of the boss on two or three seconds and sometimes you just have to stand there dodging zillions of fireballs for an entire minute until you finally find a hole and decide to attack (that is, if you manage to stay alive). Also, when the screen changes from the boss' second form to the third, you appear right over a hole that kills you instantly if you do not remember to prepare for it (the first time this happens, you have practically no way of avoiding death).
On top of that, you have to beat all four forms without a single "control point". Just a slip while dodging all these fireballs and... poof... you have to start all over again. It's too frustrating. I'd suggest putting an automatic save (using the shift) just after the second form, so you don't have to repeat the entire battle so many times for commiting a single mistake. Still, I'll give it another try later when I come back from dinner (I had to quit just when I managed to get to the fourth form). But man... that thing's just brutal
Maybe I just have really bad luck... or maybe I'm just not good enough, I don't know.