It's ambitious and impressive to see a multi-phase boss in a game jam! I do feel like the attacks need more telegraphs, since I pretty much had to just take random hits due to the lack of cue for any of the attacks (slowing down the projectile speed or making the player's movement more responsive could be a good alternative). 100 HP for the player does seem excessive at first, but with the lack of cues for the attacks, I only had like 15 or so HP by the end, so I guess it was actually a fair choice. Would love to see some audio, there are some websites that have public domain (free to use) sound effects and music if you don't feel like making your own! jsfxr is also an easy-to-use web tool for generating sound effects. Really enjoyed the creativity with some of the attacks, like the one that flips the screen, the pushing walls or especially the lava crushers!