So I've Played and Watched Aphelios...
While the champion is most definitely fun, he is extremely busted atm. His attack speed per level is pretty high, which means that he can just dump all his points per level into penetration and ad with little consequence, his flame thrower weapon also crits on the flames that it sprouts which makes for some devastating teamfight potential, imagine a twitch ult with 550 auto attack range but basically has a built in runaans, that can potentially hit more targets and slow while doing it, if your secondary weapon is gravitum.
And this is just scratching the surface.
He 100 percent needs a lot of changes atm. For starters, i think his auto attack range should be reduced (base 550), slow duration decreased, and aoe penalty on flamethrower reduced from 75 percent to 50. Attack speed per level should also be lowered.
But i will once again say, that he is extreeeeeeemly fun and satisfying...but defintely needs number changes.