Apologies for the quiet audio, for some reason this was a nightmare to capture and have good audio for so I just went with this take..
So upon losing this challenge on a NG+ Casual difficulty save multiple times to try and get the challenge done, I did a number of attempts on this boss fight to try and figure out how it was beatable as noone had seemed to publish a victory or any info on youtube yet.
What I've discovered is there is actually a strange trigger for the boss fight which must be met before anything meaningful can happen, and that is that the two archways need to be destroyed by the boss before doing damage is even relevant.
Because of this, starting the boss fight by just running and letting her destroy them ASAP seems to be the main key to completing this boss in less than 2:30, and hopefully this information wont just help you get your challenge done, but the Village speedrunning community shed some time off of this boss fight as well.
