[abel920]

So I'm stuck on world 3 with the boss. Halfway through his HP is fine, but the last half seems weird. It appears that no matter how much I dodge those rock-cannons, my life keeps on depleting until I'm literally dead.

Is this a bug, or am I playing it wrong? No pun intended.

I see some other threads discussing that buying jewels to continue to finish is a solution, but I'm just wondering.

[SuperGrafx]

That boss requires you to start the stage with the appropriate weapons.
As you fight him, you may need to switch between weapon in order to do maximum damage AND to reach his weak points. Not all beams, lasers and projectiles are created equally in this game. You need to experiment a bit depending on what you have available in your list of awakened skills.