Hmmm... puting all my personal favorite preference aside I would have to say Jax OR annie... both lore make you think they could or will get way more powerful... her Q will turn into brand ult and tiber may grow up too :O

Not that I'd seriously pick him as #1, but since Cho got the love, Morde's lore also hints at him being exceptionally powerful: ''The common perception is that the encompassing armor protects him, I fear that - for the fragile time being - it actually protects us.'' - Rozuel Fecirem, Arch Adjudicator, noted in Mordekaiser's eligibility evaluation.

And then there's Olaf. Pretty impressive when every 100 seconds, you can surge with enough power to end the world and destroy Olympus by yourself lol.

I'm pretty sure there was another thread already adressing this:

but come on- Anivia needs some love. She is the very embodiment of a world of ice. That's pretty damn powerful lol

If Veigar was competent in the least, all of Runeterra would be some random asteroids. His (arguably) weakest ability, his stun, is a black hole. He wields the power of creation at his finger tips and if he so desired, he could destroy everything rather than just steal balloons.

My guess would be Xerath.

"Free of flesh and bone, Xerath held nearly infinite power at his command"

I can only assume the Shurima mages were only able to imprison him due to the chaos the ritual itself had wreaked on Xerath.

Soraka is, both pre-retcon and after. She is the only one, lore-wise, to have been said to reach such a level. The implied meaning was a god. She had to give up her god status to walk with the mortals in the retcon. The old Soraka ascended to said status. The only potential equivalents would be those of The Void, where it appears to be an extra dimension/universe (the way I look at it). I would venture to say there are those in The Void who are more powerful than anyone else in the universe where Runeterra exists.. combined.

And @ celestial entity/being =/= deity. Technically, you're right - it doesn't always. But you cannot use DnD to support that because it's lore and what celestial means is completely different. Generally, if something is said to be celestial, it is accepted as a divine or a deity. Even in the case of it not being THE divine/deity, it is usually immediately as close as possible (in the case of an angel/etc). Celestial being can also have a lesser known sense where it can refer to space and the universe/stars. I, for Soraka's lore, see it as a combination of a deity and stars.

Udyr. He has no need for an ulti.

Olaf, he's one word wall discovery short from being the Dovahkin.

Ziggs, its only a matter of time before he goes completely insane and invents thermo nuclear bombs.

(Champion skin suggestion... Fallout Ziggs)

I thought karthus was lore wise the most powerful considering he rick rolls everyone to literally end existence of everything. He only sings about 5 seconds of his song for his ulti or so I recal. Other than that, I think xerath has the most potential for being the most powerful, considering the limits of his power are the same limits imposed on tengen toppa gurren lagann. Nothing beats f***ing spiral power, nothing ever will.