You really put a lot of juice into the animations and effects, lot of visual polish, looks very nice. Unfortunately, I wish there'd been some more polish in the core mechanics. The grappling hook just doesn't work 50% of the time (it either lets go too early or it gets me stuck in the wall) and the dash carries momentum for so long that I frequently ended up dying because I dashed off-screen, and immediately fell into a pit on the next screen. A similar problem often occured when respawning, which is so fast that it'd often cause me to immediately die again because I'd dart away just after spawning.
I fooled around with the time slowdown, but I never really found it useful. For the bosses I ended up mostly just spamming the parry/heal and using the regular attack to gain energy back, which didn't feel all that strategic. The third boss felt pretty different though, ended up using the fireball there since it deletes his projectiles.
Overall, I think there's some really cool ideas here, and I think the world design was solid. I was also impressed by how big it was, and how well the map screen worked. But if I could give you one tip for future jams, it'd be to spend more time with just a character controller in a testing room, and really iterating on it until it feels really good to control, especially if you want to make a game that so heavily relies on platforming through instakill spike gauntlets.
Still, I had fun exploring despite the occasional moments of frustration, impressive work!