Cool boss fight! Took me four tries to defeat the boss.
On the second try I got stuck underneath the boss (before I learned that space was for dodging) and died less than a second later due to all the tick damage, so maybe a knockback or something when the boss lands could solve that problem.
One thing I didn't like was that the projectiles the frog sent out didn't disappear when they hit the player. I would've liked them to disappear as I already have been hit by it and don't want to get continuous damage if I'm not able to dodge away somewhere safer.
I really like the art style! The gameplay reminded me a bit about Titan Souls and this has the potential of being in the same "boss rush" kind of genre. A solid prototype!