Nova wasn't so much brought onto the Fields of Justice, as he was born onto them. The Dragon bore a life outside the skirmishes in the Rift, in the unexplored islands that flanked it. It was on these islands that she had an egg, which brought forth a small wyrmling. This child grew up primarily on their own, with their mother often called to the Rift to serve her duty. Shortly after he hatched, his wings fused to his forelegs, leaving him a Wyvern rather than a true Dragon. As such he learned how to walk short distances on his hind legs and claw at foes with his front, rending their flesh and leaving them easy prey.
He hunted the forests of his birth-island, steadily growing stronger, until his presence was noticed by the Summoners. They brought him onto the Rift, and linked his young, fragile mind to one of their own, eliminating his childish thoughts in the process. It's here on the Rift, where this Wyvern Child shall come of age, fighting against the Champions of the League as one of their own, if not by his own choice.
This was my first time manually going through this formatting, so I hope I didn't mess anything up, feel free to tell me below if I did! Nova was created as a result of a challenge between me and a few friends, and has received a massive number of changes between the Google Document he was forged in and translating here to the wiki. The challenge was to create a champion with an ability that affects the areas in front of and behind them in some way. As for the inspiration of his ultimate's passive, I wanted to take Kha'Zix's ultimate passive and apply it to a champion in a way that promotes more diverse possible builds (though I see assassin Nova running 3/2/2, skirmisher (or diver as Riot calls it) Nova running 3/1/3, and tank Nova running 1/3/3 with very few straying from that) while keeping the abilities you're modifying unique. Additionally, I wanted to bring a new faction to the Fields of Justice... The Creatures of the Rift! His ultimate is... Well, I'm trying is all I can say here.