A Nomad 0wn3r is someone who has defeated a large, scary, and exorbitantly difficult boss in a video game. This phrase developed from the popular web MMORPG RuneScape, created by the British game developer JaGeX. With a great disdain for their nooby quest monsters that was only exacerbated by the fact that other popular MMORPGs had much more of a challenging horizon of monsters, JaGeX created a quest that changed the quest paradigm forever.
It used to be that RuneScape quests were generic and formulaic, with the central elements of puzzles and hard boos monsters balanced everything out. However, the quest monsters were insanely easy to defeat and too many people had the highly coveted Quest Cape, a symbol of how a player has beaten every quest. JaGeX, fed up with how every other game supporter vilified RuneScape for it's trite quest monsters, released a quest called "Nomad's Requiem," which is, by far, the hardest RuneScape quest in existence.
Barely anyone could defeat the quest monster Nomad. The quest monster of said quest severely outweighed the quest aspect of puzzles astronomically. One had to have maxed combat skills and sheer dumb luck to defeat this quest monster. It's taken questers, on average, 7-35 tries to defeat Nomad. Being a Nomad 0wn3r is a highly coveted title, as it indicates that the player has defeated the hardest quest monster, or hardest monster in the game.
Jimmy: Dude, that boss took forever for you to kill last night! You must be a Nomad 0wn3r!
Bimmy: No Way! I call h@x!