I'm glad there was a big boss battle at the end! You nailed the tuning for hard mode because it ended up being a nail biting fight with my health almost empty right as I took it down.
The randomization of abilities and having them be on countdowns didn't add much for me. I felt like the optimal strategy just became to constantly spam my buttons without paying attention to what was currently equipped. At that point they may as well have been triggering automatically like in Vampire Survivors, but I appreciate your attempt to be original and not copy their homework!