After Earth Man shunned the ring, Dyogene went looking for another worthy ring bearer, and wound up returning to the Legion. Cosmic Boy assembles as many team members as he can (which is….not that many), and the choice is made. Meet the successor of Rond Vidar, the newest Green Lantern, and my favorite Daxamite….
Mon-El!
Mon-El was most recently, and famously seen, headlining Superman during New Krypton, as well as filling in for the Man of Steel in the Justice League. At the conclusion to Last Stand of New Krypton, Mon-El was returned to the Phantom Zone so that he could be removed later by the Legion and cured of the lead poisoning, and has not been a huge factor thus far in Legion or Adventure Comics. Obviously, that’s about to change.
As far as Legionnaires go, I can’t think of any better for the job than he is.