I've said it before and I'll say it again in regards to properly nerfing Vayne

Silver bolts is fine, it doesn't need to be nerfed. For starters, Vayne maxes out Q first, not W. Not to mention, in early game and even mid game, she doesn't really do a significant amount of true damage.

Her biggest problem is at level 6, she presses R and gets 30 AD instantly (and the level 1 ult duration lasts 8 freaking seconds) and offsets any advantage you have statistically - and I pray for you if you are at a disadvantage. If you want to give her a meaningful nerf, nerf the AD she gets on level 1 ult by 15, nerf the level two ult by 10 and let her level 3 ult remain. I'm not a fan of harming the power of a late game champion. However, I'm ok with nerfing their early game or a spot in their game that gives them a bypass to their "weak" early game. Vayne is not weak any longer once she hits 6, it's that simple.

Change her ult to: Bonus AD: 15 / 40 / 70 AD

She is now balanced as she's actually weak early and doesn't auto-win a level 6 all-in.