I got a video if you want to see how I beat him easily with guillotine. The main thing is take a lot of block damage before using your sp2 so you can really heal reverse bahamet and gain a ton of volatility. Also easiest way to beat him in his last phase.https://youtu.be/l7TLMXE9_7E?si=z1gg35oUN_7r_YMs
Known bug they've ignored it garbage challenge