Static Shiv is the reason Vayne is so strong, nerf the item, not Vayne.
The problem with Vayne right now is Static Shiv , the item is WAY too strong, and paired with IE, you can get a 650+ magic damage crit from shiv and 450+crit from the other half of her damage, being the auto-attack, just from 2 items. Vayne herself is not too strong, its the item that is ridiculous! Shiv scales soo hard into all stages of the game! Give the item a nerf, she's one of the only champions who uses it! Its the same situation as protobelt tl;dr Statik Shiv need's the nerf, not Vayne. Shiv right now is like the DFG of adc's who use crit. Maybe make Shiv not scale damage off of IE's 50% crit bonus damage