Roxy's existence kind of raises interesting question if she soloed war against humanity how come she is not running the council at this point as it’s permanent supreme leader. She completely outclasses Asteria and Luna with their civilizations it’s not even close. If humanity with their ingenuity got taken out by her I don’t see any way civilization based around body builders and warrior culture would have any hope of lasting any better than humans. It does not matter if you can bench press Abrams tank if you are fighting something that can just ignore straight hit’s from nuclear weapons. Physical strength becomes irrelevant in that situation. Luna may have some mystic science fiction weapons but they would probably be still bound to mostly same rules to what humans must have tried to use against Roxy. So if Lunas empire went toe to toe with Roxy I would say it would be more likely Roxy would come on top. Morganas power is a question mark because she is implied to have the artifact that completely outclasses her and would highly likely outclass Roxy in any engagement. Question who would win between Roxy and Morgan comes down to how much power Morgana can actually get out of the artifact if fight actually broke out between the two. I would still say it would be probable Roxy would overpower Morgana because Roxy had power to take down humanity her power is proven. Morgana is in active competition with Organization institution inside humanity. It can be assumed that similar Organization in Roxys timeline or dimension threw its weight behind humanity in that engagement and it made no difference. So unless there is some kind of rock paper scissors thing going on I would say Morgana would have no hope to do anything to Roxy in any engagement. Quarinah outclasses Roxy completely there is no question about that but only in dream world. Quarinah has done nothing that indicates she has similar powers outside dream realm. So if Roxy would start throwing her weight around I would not see Quarinah being able to do anything about it unless she managed to fool Roxys physical body to enter inside Quarinah demesne. At that point Roxy's aspirations would be instantly over. Reason why Quarinah would not bring forward same problem as Roxy is Quarinah's power is highly localised I don't think she would be able to go on a rampage in real space like Roxy also other dimensions don't have anything Quarinah already does not have. So Quarina would lack motivation to move anywhere else.
This also makes questions about beginning of the game. Roxy was in the council meeting at the beginning of the game. I’m assuming meeting was in Earth in Morganas demesne. How did anyone manage to convince Roxy to go back to her dimension. That's a legitimate question because there is nothing there it’s a wasteland. She has no subjects, friends, family, responsibility's or any real ties to that dimension that would keep her there. After she got transported first time to Morganas demesne or to any other demesne(Not including Quarinah demesne) what prevented her from just saying” I like this place lot’s of things to burn. I think I’m going to move here. What is that look? You don’t like it. :) What are you going to do about it? XD”