En Dwi Gast (Earth-TRN517)

Three billion years ago, a young En Dwi Gast went on a exploration trip with his fellow Elder of the Universe Taneleer Tivan and his daughter Carina. After passing through a storm between realities, En Dwi and Taneleer found a "nexus realm" abundant in ISO-8, crystals theorized to be all that remained from the cataclysm that destroyed their universe. Using their spaceship's equipment, they traced the quantum footprint left by the crystals to an apparently dead Celestial fused to the core of a planet.

When Carina landed on the planet's surface to collect a sample of ISO-8, En Dwi was separated from Taneleer by the planet's explosion and became stuck on a rock that spinned free of the planet's gravity. While he eventually broke free of it, En Dwi was still trapped in an unknown realm with no spaceship nor working communicator, which meant he had to to walk home; however, due to space-time being fragmented in this realm, En Dwi would travel years back in time or be transported a hundred miles in the wrong direction every few steps he took. He had to solve the largest puzzle in all creation just to be able to return, and that made him into the Grandmaster.

Contest of Champions

At some point, the Grandmaster returned to the nexus realm he once was trapped in and staged a game called "Contest of Champions" there which eventually earned the realm its name: "Battlerealm." All the battles took place at the Galactorum, a coloseum created by him on the Battleworld's orbit. Under unknown circumstances, the Grandmaster ended the Contest and closed the Galactorum, leaving the Battlerealm soon afterwards.

Titanomachy

After discovering his brother had restarted the Contest of Champions behind his back, Grandmaster returned to Battlerealm in order to confront him. As the Collector introduced a Summoner to the reopened Galactorum and the second phase of his contest, Grandmaster arrived and quickly put the entire Battlerealm against his brother, who just managed to survive his traps thanks to the help of the Summoner.

Seeing his brother was no match for himself, Grandmaster challenged him to a Contest of Champions where the winner would become the true and only master of Battlerealm and the loser would be banned forever, using just one of his champions, Loki, to battle him.

En Dwi Gast (Earth-TRN517) from Marvel Contest of Champions 003

Gods of the Arena

At the behest of a Thor who wanted to restore his own honor, the Grandmaster organized a tourney where Thor and his partner, the Summoner, would be pitted against the many Champions of the Contest. Although the tourney was briefly interrupted by the arrival of Hela, it continued as planned, reaching its end in a glorious battle between Thor and the Summoner.