Dragon is effectively something like that.
Very common story for overpowered characters
The Empress is not playable.
She is at the head of the Equinox world. Actually, we don't have a lot of information on this world.
Equinox people were on Guem in the past when the door of infinity were opened. They tried to rule this world and were defeated. But we don't know exactly how they were defeated.
It seems that eltarites (like ) were engineered by Equinoxians as their primary strike force. Daïs, helped by the World-Tree, defeated the Eltarites dividing them into Elfines and Hom'chaï.
As this event blocked the door and the power of the Equinoxians ? This is actually unclear.
Perhaps Dimizar will explain all this stuff in the future.