How do I beat the dragon in Castle Keep?

In Candy Box, How do I beat the dragon at the end of the castle keep level? Even with a Level 2 sword of life, starting the fight with an invincibility buff, and 170hp I'm only getting it down to 700hp.

Solution 1:

The way I did it seems pretty fool-proof. I just ran in and popped an invulnerability potion right before I touched the boss. Then when it runs out teleport back. When you get to the boss next time, the timer still won't be up though, so you'll have to use another teleport scroll, but then the next time you can turn invincible again, and repeat the strategy until victory. It's pretty costly, but the winnings will pay for it easily.

Solution 2:

I guess my way kind of sucked, but I kept eating candies until I got up to around 1000hp myself, then just kept drinking major health potions whenever possible.