Theories of the dark star (Every dark star/dark cosmic so far)
Dark star thresh - The harbinger Thresh seems to speak constantly of the world being devoured by the dark star or really in theory, a black hole. It is as if he is fortelling that runeterra will be obliterated by a black hole constantly. Thresh also seems to be able to warp reality as we know it, being able to not only create, but also travel through black holes, who knows what else he uses them for aside from transportation and implosions. He represents the gravitational pull of a black hole, which of course makes sense because he has a hook that pulls people in, he literally speaks "there is no escape"
Dark star Varus - Life ender Varus is a bit confusing since there isn't much to look at, but what we can easily see is his "scarf" and his arrow are somewhat similar in a way being identical to a star or comet. Imagining the impact of a star hitting a planet, even merely interfering with another solar system spells devastation enough, which seems to be varus's job, bringing the end to solar systems.
Dark star Kha'zix - Realm Render Kha'zix is simple to look at, he is slicing across the surface of a planet. Kha'zix brings end to planets as he pleases, representing how unrelenting outer space can be at times, destructions of stars, black holes engulfing stuff, etc. Kha'zix is similar to varus, except kha'zix is more direct with destroying planets and its life.
Dark star Orianna - Tactical Termination Orianna, as we see in game and in her art, shifts around the position of a black hole (or black hole device). It is as if Orianna seems to be placing black holes to their main destinations, either just because they need to be there, or the end of a solar system. Orianna as it seems, isn't as relentless as the other dark star, but it doesn't mean she isn't destructive.
Dark star Jarvan IV - Shattered life Jarvan's art and design shows something unique, most dark star are grotesque and horrific beings, but Jurvan is almost human-like. Jurvan seems to represent when a star reaches its finale, and collapses in on its own mass, imploding into a black hole. Instead of holding a black hole (ignore the one in his lance that is not what I am talking about) he is holding a regular solar system, as if he watches for suns to reach their dying ends.
Odyssey Kayn (Dark Star Rhaast) - Gateway to Desolation Rhaast represents the devastation, desolation, and destruction that a black hole creates, or the carnage and casualties caused by a global impact from a comet, supernova, so on, all we can say for sure is he represents destruction. He says numerous times he will destroy reality, similar to thresh, but he will destroy without warning. He wields a shattered scythe that of kayn's, and uses his body, similar to a sun collapsing in on its own mass (we even see kayn LITERALLY implode into the dark ora sphere during the rhaast transformation), like jurvan, except he doesn't look like his chest exploded outward like slave knight gael from dark souls 3.
Dark star Shaco - Foul ploy Shaco in his login screen looks similar to kha'zix's positioning, but he isn't attacking the planet directly. It is as if shaco watches instead, looming over solar system, driving them into fear with false tricks of threats of destroy life of a planet, similar to constant worry of people that a black hole will appear suddenly and engulf our planet. However, there is a vortex shown in the login screen on the planet, perhaps it was humanity that caused it in response to the fear of destruction.
Dark star Karma - Isolated Singularity Karma represents the stationary positions of black holes, showing there is nothing to fear of black holes (unless a star implodes near a planet) unless you dared to come in close. Karma in the image looks peaceful, without any view of planets being destroyed or toyed with, as if karma is just left alone as she should be, not to be bothered with.
Dark Cosmic Jhin - Reduced and Reborn (finally my favorite) Jhin represents the constant cycle of destruction and reconstruction of solar systems and so on, like a wound that heals over time. We see that jhin is destroying planets, as all dark star would be, however what is different is that there is a beautiful scenery down below, as if Jhin created it out of the destruction he ensued. Not to mention, he is a dark star and a cosmic combined, meaning he is both destruction of a black hole, comet, dying star, etc; and the life that a solar system contains, he is both.