"OMG VAYNE IS OP"

You do realize it is ONLY because of how strong tanks are right now right? Shes probably the only ADC who can deal with tanks with her percent max health damage + self-peel (which makes her less reliant on her team and allows her to survive a dive from a Volibear and Maokai with 4k health, something very few ADCs can do).

Once the tank meta fades away she'll be back in the ides of mediocrity. Literally every other meta makes her useless. The Tanky DPS meta annihalated her, Assassin meta destroys her, etc etc.

This being said, she needs a nerf to her ult in her first rank or two. This would fix her insane power spike at level 6 which allows her to duel any ADC in the game. Her midgame is too safe and yes, I am a Vayne main and I agree that this would be an adequate place to hit her. A 10 damage reduction on her ult at rank 1, and a 5 damage reduction at rank 2, and leaving her rank 3 alone would fix her problems. Or perhaps reducing the duration at ranks 1 and MAYBE 2 (and leaving rank 3 alone) would also be fine.

Nerfing any other part of her kit would either destroy her identity or make her laning phase unbearable. Her Q, W, and E are FINE. Its the free BF sword you get with your ult at RANK 1 that is the problem.

Im also guessing Riot is PURPOSELY leaving her alone because she is one of the only adequate champions who can deal with tanks.

Dont gut my Vayne though thats the last thing I want. If you really want to deal with her you can place a pink ward when you fight her and watch her cry. Or pick Xin Zhao/Malzahar/Fizz/Warwick/Whoever and dumpster her in teamfights