The attacks that you claim to be real difficulty are scripted. Boss starts casting move, ground lights up where you need to not be, you move out of it before casting ends. You have seen the move before and know exactly what it does.
Part of the practice and memorization of a fight is practicing dodging. Anyone can dodge when there's a small number of attacks that the boss can do and they are telegraphed, just the same way anyone can memorize a fight.
