the ancient crystal were in the hand of different kinds. Humans, demi humans, gods, and monsters. But the gods decide to collect and rule the world, they killed and collects the crystals that gives them an infinite power but its too much that they can't control and died. as the other gods died, the crystal were separate and fly in different unknown places. There are 4 powerful crystals that were given to different kinds. Humans, demi humans, monsters and gods. The crystal known as "4 Celestials crystals that were known as fire, water, wind and earth" It's given to the 4 celestial of humans, demi humans monsters and gods. But the gods decided to take the crystal to reign and rule the world they killed and take the 4 crystal and gain the most powerful power that no one can ever had. Many people died as they fight for there freedom from slavery and ruling of gods the war last 1,354 years of ruling and the crystal were surrendered and given back to the celestial and ended the war between humans, demi humans monsters and gods. "i once trusted a star dragon but now, I trust metal more!"  the last word of the last warrior who fought alongside of humans, demi humans. As the sky turn red and shallow, the humans stand up to bring back the rights and humanity that gods once took to them.

Since the first day of the apocalypse there's always be a defenders and variety of warriors/soldiers They fought against the mutated zombies.