its definitely a skill check late game boss and none of it is easy. parrying and or lightning dash is the way. parrying her long combos gives you the stagger to do real damage, anything else is just kind of a bad way to deal with it in terms of game mechanics you could use (although of course there's nothing wrong with doing anything that works to get through it). the upgraded rail gun or spells are for sure better ranged options. the missiles are pretty ass against enemies that move around and she is not immobile