I think some of the possible reasons (in my view) people leave midway through Onslought is - 1) Going into a game and players rocking two primary weapons. 2) Players keep dying and don't always have the right builds to stay alive. 3) People are NOT using their supers (creating orbs helps the wider team). 4) I think during the first 10 waves, you kind of get a better understanding on how well you would do as a team. In some instances, we have melted the first 10 wave boss within minutes, and in other times, it has taken way longer than it should have. 5) Having saved loadouts and able to change loadouts with a click of a button is very helpful too.