Thank you for playing the game and for your feedback!
I agree that the Sylvan Dragon currently feels a bit too durable compared to the other regular enemies. I'll be making some adjustments to bring it more in line with the rest of the game's balance.
For now, Thunder Scrolls are the most effective way to deal with Sylvan Dragons. If you're short on money, Sleep Scrolls or Silence Scrolls can also make the fight a bit easier.
As for the Ruby, it can be obtained by defeating Red Dragons.
