Crestfallen Infinity spell only obtainable if no Life Capsules are obtained...
(Life Syringe, different story... so 14 max HP instead of 4 max HP can help, but completing Ririn's quest is needed to get the Life Syringe...)
Beating Qwertyuiop with that spell and the Lazerbear gun was a bit... too fast, but the bosses' HP (floor 30, Eminent Arena, Oblivion Zone, Red Hell) are not yet finalized or edited...
Crestfallen Cool is the "limited mana" version of Crestfallen Infinity...
I'm aware of that, I was mentioning how easy it'd be to miss because most players wouldn't know about it on their first playthrough (unless they're going out of their way to find every secret in Apocalyptic Shaodw).
If beating Qwertyuiop with the Lazerbear and the Crestfallen Cool makes the final boss easy, then perhaps it's a sign that the bosses's HP needs to be raised.