i think i found a secret skill she has, on android at least, she can "zombify" ophelia(and maybe others) if she does the final strike, letting you defeat her over and over as long as you can keep defending and let her do the winning blow, heck it even unlocks the menu so you can save in that battle, the only thing you lose is the ability to see the stats and what ophelia is going to do next, so you need to memorize how much hp you have left even if defending reduces all damage to zero because of another bug, if noelle does lust damage when ophelia is trying to counter you get two points of damage
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i got from level 3 to level 12 before getting bored