If you can't defeat the Demon Beast:
Here's a couple hints:
- Destroy all of the orbs before attacking him, or else he'll be invincible.
- Before you destroy all the orbs, like while you're destroying the one at the top of the mountain, you can jump over the Beast's mouth and dodge the fireball.
- After you lower his life bar, he'll explode and Demon Eye will appear. But don't worry - He can't hurt you. Just pound the crap out of him and he'll die. You win!