Centuries ago, there was a realm. It was the most advanced realm in their time, an it was called the Human Realm. It was a realm that stood out the most since they had the most advanced organisms and life form that can not be found anywhere else; humans.
These humans were a happy race. They had homes, families, rights, and basically everything and anything you need to survive.
Then there was this one scientist, named Gilbert Shnogg, who created an elixir that's can give you the power of any chosen supernatural being. He introduced it to his peers and quickly became famous, both him and the elixir. When the leaders of the supernaturals heard of this, they were outraged. No one was supposed to posses these powers except the proper species. If everyone were to drink that elixir, and become a supernatural, it could throw off the balance of supernatural and humans, and cause wars.
But they decided to leave them be, and see how it would play out. (A pretty stupid move, I'd say, considering what was going to happen next.)
But the elixir became more and more popular, as more and more people drank the elixir and became supernatural at will. Soon enough, little battles and mini wars started to break out, whether it was human versus supernatural or human versus human. Soon after those wars and battles, a new war came to be, this time, all of humanity against supernatural.
So the supernatural leader devised a plan for the war and to stop the elixir from spreading and went to work.
First, they appointed a leader to lead them in the war. His name was Avis Shumanni. He was unlike any supernatural being. He had the power to persuade and rally every known being and organism to do his bidding.
And so the war began. Humans against supernatural, bloodshed on top of bloodshed, agony and despair raining across both sides. Finally, after a hundred years of war, supernatural won and the Human race was wiped out. Gone, never to be seen again.