Hello to all persons who read this. At first I want to introduce myself. My name is Auctoribus, Im 17 years old and Im from Germany. I will try to show how I think to play Vayne. I hope you guys can understand everythink what I want to say and I hope it will help you a little bit. But when you compare my itembuild and guide with other itembuilds and guides of Vayne, you will see some differences. Try it and look how it works. Have fun.

Pros'

-Awesome damage!
-Can stun with her E
-High mobility with her Q
-Can get unvisible with her ult and Q
-Tank-Killer with her W
-Low cooldowns
-Best ADC in late game

Cons'

-Hard to play in early
-Need a lot of farm
-Get often focused
-Very squishy

Now we come to the runes. Lets start with the red runes. I took because a ADC needs AD and the red runes have the most AD of all default runes. You should take 9x Greater Mark of Attack Damage to get some AD at beginning. For your yellow runes, you should take Greater Seal of Armor to get some armor at beginning to get less damage. For the quint you should take Greater Quintessence of Attack Damage to deal more damage at beginning. At last come the blue runes. There you should take Greater Glyph of Scaling Magic Resist to have a little bit more magic resist at lategame.
I think this runes work fine with Vayne.

I think you wondered when you saw my itembuild. Maybe you think that I forgot the boots. But I didn't forgot them. I always play without boots. Vayne don't need much movement speed. Vayne has a basic movement speed of 330. My 2 phantom dancer give you 10% more movement speed. So you have 366. When a enemy run away from you, use your Q to follow him. When someone follow you, use your Q to escape. When you play without boots, you can buy one more item. I took one bloodthirster more. So you have 70-100 AD and 10-15% lifesteal more. Thats awesome! You have a lot of AD, lifesteal, crit, armorpenetration and attackspeed. Thats all what you need with Vayne. With this, you can kill everybody(when you have a good team)!

When you play Vayne, you should have a tank in your team. Always stay in team and hope that your team is usefull and defend you. I think that you dont need a real supporter. A lot of "non supporter champs" can support you too, for example Shyvana, Zed... I think that they should get some farms too. You should get 70% and your support should get the other 30%.

That was my first guide. When you want, try it, when you dont want, dont try it. I hope that I can help someone with this guide. Have fun with testing it ;P