This world once held the center and source of all magic. None who remain on the world know or remember this. A world of vast oceans and a singular continent that held the magical Kingdom of Solace. In this kingdom was the fountain of mana, the source of all-magic. The opinions over who should have access to this source led to a war. Any record of what happened next is lost. What is known is the Grand Sundering followed.
The Grand Sundering was the unnatural formation of the Grand Scar, a massive geological fissure that spans nearly half the equator of the world. Geologic markers show that massive oceans drained into the center of the world as the Grand Scar formed. The massive gravitational shift pushed most remaining surface water to the poles, where it froze solid. The surface was pushed and pulled and eerie and dangerous land formations remain.
None survived the massive changes across the world. Wild-magic remnants of that world sometimes pull random people and creatures to the wastelands. Not many survive, but over countless millennia of these random occurrences led to small colonies-of sorts. A powerful wild-magic Sorcerer calling himself 'The Grandmaster" built the first Arena-World. He exploited these early colonies to build a massive arena complex on a large plateau at the center of the planet. He employed wizards to teleport spectators and gamblers to view the games and became wealthy enough to claim dominion over several realms.
That is until a young protégé of his killed him and took over. The Grandmaster had led his Arena-World for hundreds of years, enough for the world's culture to change towards serving the Arena Battles, instead of lamenting. The newly appointed Grand Leader refocused this cultural engine to create he own vision of the Grand Arena. Instead of having to employ untrustworthy wizards; she discovered stable portal magic that expanded the number of worlds that could access the Grand Arena, expanding the profits to unimaginable levels. Inside the Arena is one of the most profitable combat arenas in the near cosmos. This distinction has come with the slight notice of some Gods. These gods sometimes test Grand Champions with an arena of their own.
The world outside The Grand Arena has remained remnants of the apocalyptic cataclysim. Wasteland and barren, affected by wild magics, natural catalysts allowing insanely difficult beasts to evolve.
The Grand Leader discovered "water-creation" magics which is a primary reason none have ever attempted to usurp her in her thousand-year reign. Her ability to maintain the stability of the Magical Spring, which supplies the entire Grand Arena Complex with plentiful fresh and potable water, keeps her solidly in power. Her stable-portal magics giving access of countless worlds for import increases this power. Although she is harsh and pragmatic, she is rarely ever cruel. Rarely-as she has shown cruelty at least a handful of times in the last thousand years. Legendary cruelty that has held to be more than enough to maintain fear. Her ability that maintains a livable complex on this otherwise inhospitable world has turned the Grand Leader into a near-divine idol from many who dwell, work, and serve the Grand Arena.
The Grand Leader maintains a strict Import control over her portals ensuring her technology remains the most advanced on the world. Some portals can destroy advanced tech immediately. Others will merely sound an alarm, letting the sentries retrieve the offending technology. The area around the Grand Arena is patrolled by sentry-bots ensuring nobody unauthorized leaves as well.
The Grand Arena is known in almost any world that has both high-rolling gamblers and magics strong enough to create portals. The stability and number of portals that exist within the House of Portals boggles the intellect of even the most advanced portal wizard, adding even more tourist-reverence for the Grand Leader
(Hidden Lore: The Grand Sundering)
The War of Mana was indeed over who could access and gain the powers of the font of all-magic. The King knew of its destructive power and held-fast that only a few selected could ever possess the font's power. Rival forces laid siege to the kingdom. When all hope was lost, the King did the unthinkable. He and a small number of his royal mages transformed the font of all-magic into a new form, one that could escape the reach of those on the world. The resulting spell created the seed of all-mana. The gravity created by such a seed tore land from the planet surface to form a protective mass, the seed and the new land flew high into the sky, out of the reach of those on the surface. The land which is now the "Floating Forest" is the land torn from the Grand Scar. The formation of the nearly inaccessible skyward forest destroyed the world in the Grand Sundering. None of the kingdom survived, nor the rival faction that hoped to claim power. The citizens who live on the Grand Arena's world are the result of countless millennia of wild-magics pulling random creatures to the wastelands, None have been curious enough to investigate the Grand Scar enough to learn how it was formed.
(Hidden Lore: The Grand Leader's Cruelty)
Early in her reign of the Grand Arena she realized the growth would overwhelm their ability to keep the Grand Arena clean enough to attract and keep High-Rollers. She gathered weak and poor from several less-than well-off worlds and cast them out into the wastelands. She left them with nothing but the proximity of the exit of her new Grand Arena sewer system. The post-apocalyptic wastelands held no easily accessibly surface water, so this waste was the closest thing the abandoned ones were going to get. The slums outside of the Grand Arena have built up a small but healthy culture processing and recycling the waste from the Grand Arena. These slums sometimes put up resistance or rebellion against the Grand Arena. Sometimes the Grand Leader has put these down with overwhelming force, and sometimes she has quelled the rebellion with deliveries of clean water and crates of food.
Over the past few hundred years the Grand Leader has noticed the high evolution of the native Scavs. She is frightened of what this native race represents and has taken some steps to potentially shut-off or quell their spread. Although recently she has begun to reconsider her positions.
The Grand Leader once did research into the remaining wolf population, her experiments seemingly caused the extinction of the world's wolf species. (The few remaining just learned to hide really well) The Grand Leader only abandoned her research after she learned the "Way to Paradise" was a way to "remake the world" a feat that, in her mind, she had already accomplished.