You know, as much as we like to point out lore inconsistencies, you have to give props to riot here

Remember how 2 years ago (or 1? maybe that was around the star guardian event's time) people were clamoring for star guardians and dark star to be in the same universe, the latter being the "otherworldly monsters" the magical girl team would fight? They knew ahead of time that they were going to create another skin line that would have something to do with dark star and that jinx would be a part of both, which would have caused confusion were they to be in the same universe. Good work riot!

Now they only have to explain how kayn is supposed to be serving Under Jarvan IV's command when he's a dark star. The skin lore states that he's "A mortal emperor unbound by the destruction of his world" which is fine and all, but in-game tooltips also say that the demaxian empire lost their homeworld a long time go and that's why they're huge jerks. So how does this works? Is the empire being led by a literal monster...? Is he supposed to transform later in the story, after kayn's future is sealed? Meaning rhaast cannonically wins and destroy more of humanity, causing Jarvan to give in to the dark star?