Knight of The Cannon

Life was perfect in the country where dragons and humans lived together for centuries until one day magic storms came from a castle of The Dark Lord. He cast a spell on dragons. The mighty protectors of humans fell asleep across the whole country. The cities were ruined by thunderstorms and people are hiding in the caves. Many tried to defeat The Dark Lord and failed.
The Dark Lord is almost invincible. His only weak point is his heart. Knowing that he created himself many hearts and placed them in hiding places. An old wizard found a way to destroy the hearts. He created a magic cannon. He needs a knight who can face The Dark Lord and his magic.