someone help me out here, if his abilitys mean anything then he can create dark matter, a event horizon which leads on to mean he can create black holes, and if lazy research isnt wrong his ult (primodrial burst) can manipulate if not entirely controll the powers of creation itself (please correct me if im wrong)
dosent that mean the tiny master of evil has power compairible to a actual god of creation? (
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again please correct me if im wrong here
Veigar is as strong as the writers say he is. Really analyzing anything is kind of a moot point until we get some tangible data.
I've heard arguments claiming that he is actually stronger than Sol, because he can corrupt what Sol can make. But honestly, I think that argument is a bit silly.
Yes creating dark matter and black holes sounds very, very impressive. But, I would use as a counter-example The Blob from Marvel comics. In (admittedly only one version) of the comics he actually can control gravity, which is an amazing fantastical ability. But he can only control the gravity of things within 10 feet of him, to make them mildly more likely to feel drawn to him, on the whole, not all that impressive. Veigar could be the same way, a power that sounds unbelievably impressive in broad strokes, but is really very limited in practice.
Or he may be strong enough to destroy all of Runeterra. We won't know until Riot says so.
Personally, since I prefer a lower power ceiling, since once you get to planet destroyers the setting just starts to get ridiculous, I'm hoping he's more limited. But, Riot has shown to quite like the type of characters I don't, especially recently. So, who knows, he may be Veigar, Destroy of Solar Systems come his lore re-write.
My theory is that he has nearly unlimited power, nearly to outmatch Sol, but doesn't know how to use it. And the power he uses in the Rift are like an extent of his powers overall.
Chances are much more likely that he can corrupt a very very very small amount of cosmic energy, and then embellishes the hell out of it. I mean, if he could actually create Dark Matter or Event Horizons, Runeterra would long be nonexistant.
I think he is the most powerful mage of all Valoran.
I mean, his passive tooltip says so!
About what his magic is base don, i won't count too much into that - the spell event orizon does not resemble a black hole and probably is just a badass name, while the nature of his spells can' t say much about him either. He just kinda corrupts here and there, but we don' t know actually how much. He is able to create a corrupted Sol out of thin air? Maybe. Or maybe not but he goes close!
Overall I think veigars story will pretty much go similar to how he is presented ingame: At first his power won't be that strong,but over time he'll actually become really powerful and a credible threat.
Believe me 
is super strong if y know to play!
I will let Veigar answer this question:
He doesn't actually do those things.
Take Event Horizon, it's clearly a cage. One that is sometimes made of Christmas Trees. Veigar just has a love of astronomy.
Veigar is legitimately an incredibly powerful mage. I wouldn't take the names of his abilities quite so literally ("Cataclysm" doesn't end any worlds, the Sun doesn't actually move everytime Leona casts "Eclipse"), but he's definitely up there in strength.
The problem is that he's too much of a bumbling dork to really like...use it. He instead prefers these incredibly complicated plans, (See the JoJ), like stealing a factory load of balloons and strapping them to something so he can fly away with it. Veigar is a bumbling cartoon villain, and it's wonderful.
It has already been expressed here, but I figured I would chime in and say that we only know how powerful a champion is by what they have actually done. Just because Nasus is a large jackal-man has no bearing on how powerful he is. We only know his powers of wisdom, withering, extended life, etc. from reading what he has actually done it the lore.
For Veigar, what has he actually done. Sure, he might have the potential to manipulate gravitational/cosmic/astral energy and matter and space, but unless he actually does it it is kind of insignificant what he may or may not be able to do at some point in time. When comparing him to Aurlelion Sol, I think the important part to consider is that you can tell from Sol's demeanor and story that he actually travels throughout the universe and actually builds stars at will and actually has an immense amount of power. I can't say the same for Veigar.
Good question though! I feel like people as these types of questions all the time, and it generates nice LoL discussions 
