Guide to defeating boss in hard mode: Try to keep on using simple attacks by spamming A all the time (do not use W since the boss keeps on moving it's pretty worthless), if you get bored you can add D to your combo. If the boss falls off the ledge, use a jump attack to skill fully evade his attack in the right time (this might take some practise) and use jump attack on all his other skills as well.
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