Nice, thanks for your feedback. Yeah, good point regarding how you unlock abilities. For a game, I'm thinking about the option to "train" or "fight small mobs" to get stronger and bosses will be really hard.
I also like the idea of having achievements/quests to unlock additional abilities. E.g., interrupt 10 abilities to unlock the option to select which ability to block.
The bosses are very basic at the moment; we could definitely improve on them and make them more complex and interesting. Building in different phases would require the player to create rotations for each phase, etc.