The only additional context we have is that Crescent tells Ren shortly before he joins is that “Anger is motivation” and then has a talk with him, which we don’t see. Given that Crescent appears to despise Xen, she probably had ulterior motives in manipulating the emotionally volatile and devastated Ren and convincing him to join. Hopefully we’ll see more about that in V11.
As for the tournament, it is very likely that we won’t win it or even get to see its end. It’s possible that it was a ploy from the very beginning, or that we might be attacked.