Ahri doesn't really fall off lategame. But if you try to do more than what her official roles make her out to be you will get burned. Also if you die a lot you will have some troube catching up.
Ahri is officially a mobile mage assassin.
Ahri is unofficially an awsomesauce AP carry. Yes, awsomesauce is an actual unofficial attribute she has.
Anyways read and completely understand the roles of mages and assassins are. Ahri is always a strong mage and assassin. If you buy her because you want an AP carry then you better be really good or yes her late game is not for you.
The reason being that she has some difficulty against superlategame tank builds and she will almost always be squishy unless you give up power to make her tanky. But most tank items can be a waste on her since she has good escapes and evasion for avoiding heavy damage, even lategame, anyways. This is why things like RoA are wasted on her even lategame. Ahri is the pinnacle of glass cannon mages. You gotta put everything you've got into your lategame attacks or yes she will in fact 'fall off'
So you could say this. Ahri never falls off. Her summoners just can't always satisfy her needs lol.

Lol Ahri Does No Dmg Work

Nov 06, 2019  Ahri Guide for League of Legends. Champion guides for the League of Legends champion Ahri.Created and rated by players, find the best Ahri guides that will teach you which items to build, runes to select, tips and tricks for how to how to play Ahri, and of course, win the game! (this option would improve ahri's cooldowns)(or in stead of cooldown she would get some mana back becouse ahri quickly has trouble with mana) 4. Since like I said Ahri is a kumiho (Korean ninetailed-fox) she normally kills human MALES. So it could be possible to bring back ahri's 20% ap dmg boost on her charm but only against MALES. Jul 09, 2012  Late game vladmimir deals almoast no damage against champions my transfuzion dealt about 300 dmg agains champions with 250 ap and lvl 5 skill (oriana witn no mr items) so please buff him atleast that much that he is playable you cant compare him against veigar with his massive dmg and to le blanc or any other mage.