Looks like I can talk about Vayne without getting mass downvotes now...
Obviously what Riot is trying to do with Vayne won't work and it will cause her to probably get back into the meta and dominate. I've been talking about Vayne as a character for awhile on the boards where her kit is so feast or famine that she just needed a rework. An ADC dealing true damage who can peel for herself, assassinate her opposing ADC and deal massive damage to tanks when used properly is just too much. It isn't like the "Yasuo effect" thing, though. I've gotten garbage Vaynes on my team that have no idea what they are doing, but the godlike Vaynes dominate my games and carry for me. Her kit just makes it so hard to pop off when you don't have 800k mastery points on her. Now, it won't matter anymore. She will carry games regardless of how good the player is. If you want Vayne to maintain a good winrate without being such a feast or famine champion, stop buffing and start reworking.
stopped working. As long as that is still present in her kit, along with her passive and ultimate she will always be good at assassinating her targets. Btw I am aware of her weaknesses like her being squishy and relatively low range, but a good Vayne, like I said, can completely negate these flaws.