Inscribed Purple Prophecy

In ancient times, three terrible demons came to our world. A group of druids who mastered the power of Avalon launched a fierce struggle with them. Many druids fell among this powerful and indestructible creature. In the end, the archdruid was forced to use black magic to bury the demon in a cave to prevent him from ruling the world. Later, a prophecy appeared that whenever comets hide in the shadow of the moon and the space turns purple, the shackles of magic will be broken, the demons will regain their freedom, and chaos and terror will rule the world again.