Hey, Community!
This is my first Guide, so it wont be the best i guess :)
But still ill tell you guys something about me first. My Name's Leo, and I main ADC. Im Currently in Diamond 1. I also want to say that English isn't my Language, so im sorry for the bad english, i hope you understand it. :)

Diamond 1 and Vayne Main


Vayne:

Vayne is a hypercarry and hard to master. I wont pick her against good laners, because Vayne has a hard time in laning phase, and needs to get in to Lategame to carry. Preseason Vayne is pretty much the weakest ADC, because she got hit hard with the last nerfs. Still if u master her, she'll be one of the strongest.

Marks

Really no other options here, you need the extra AD, for better poke and to lasthit better :-).

Seals

As Vayne, your most likely going Bottom Lane, so you will need the extra Armour, because you're up against another AD Carry.
Without these you would get bullied out of Lane, and couldn't trade with the enemy.

Glyphs

I Like going for Flat Magic Resist, because in this Meta the enemy Support can get really painfull at early game. For example against Annie, LeBlanc etc.

Quintessences

Lifesteal, you're going to need them to sustain the Lane. You're Vayne, you need to get to Lategame and not get bullied out of the lane, without being able to do anything.

Start Items:

Doran's Blade Health Potion - This is the best AD Start possible, you get AD, Lifesteal, HP, and HP regen.

First Back:

Vampiric Scepter Please try to buy this Item ASAP, with this Item you will be able to Sustain for the next big Item.
Berserker's Greaves This Item, gives you MS and AS, both very important stats. AS for the Silver Bolts W procs, and MS for the Night Hunter passive!

Mid/Late: / /

Blade of the Ruined King By far the most popular build to go on vayne right now. This is because this item gives.. well, everything! Vayne scales extremely well with attackspeed because she deals true damage every 3 auto attacks. Not only that - but this item also gives a pinch of AD, and a passive that deals current HP % damage on every attack - which makes this an excellent mid game item. But that's not all.. you also get the active, that makes you a GOD at dueling 1v1 situations, which means your target should not be able to run away from you with the active. And of course, you can use it as an escape tool as well. This item gives you a LOT of options!

Bloodthirster People forget how good bloodthirster was on vayne. This item gives a whopping 100 AD (at full stacks), as well as 15% lifesteal - which makes it the absolute best item for dueling and sustaining. You will also need to change your skill order to maxing Q first because AD scaling on your tumble is really good. I go BT first occasionally when I feel like I don't need the active from BOTRK.

Statikk Shiv/ Phantom DancerThis is honestly personal preference. Statikk shiv will provide you with extra wave clearing capabilities, where as phantom dancer will give you a higher single target DPS. It's also worth mentioning that Statikk Shiv is slightly cheaper, and sometimes if I only have money for a Shiv then I'll just get the Shiv so I can finish off the rest of my items a little bit faster.

Last Whisper- Always get this Item without any exception, this gives you some nice AD, and the best you get

40% Armor Pen

, You may not believ how good 40% Armor pen. is, but it pen. almost everything along with you're masteries.

Infinity Edge- This is the best Item for an ADC, you get insane DPS, Crit Chance and Crit damage, a must for every ADC no matter what!

Last Game Item Situational:

There's two options on which skill to max out first, Q or W.

Going tumble first will lower the Cooldown to 2 seconds at max rank. If you're rushing a Bloodthirster which gives you a lot of pure AD, you're obviously going to max tumble first because tumble has really good AD scaling.

Going silver bolts first, will deal additional damage for the 3rd proc of silver bolts - which mean more base damage, as well as a higher true % health damge. The reason why this is so popular nowadays, is because when an AD carry trades with the other AD carry, they usually trade for about 2~3 auto attacks, then back off. Which means you're going to be looking to trade a silver bolt proc every trade. Maxing W first will give you a higher damage trade compared to a tumble first build. So heading into mid game, maxing W will definitely deal more damage overall, as long as you continue proc'ing silver bolts on the same target.

Condemn is always maxed last because it's mainly used as a stunning/knockback utility - and even at max rank the cooldown is still 12 seconds, which is still a really really long cooldown.

Night Hunter (Passive)

An extremely good passive, which gives you movespeed whenever you're moving towards a visible champion. This makes it extremely easy to chase down opponents! Remember that when you have your Final Hour active, this passive is TRIPLED, meaning you can virtually chase down anyone that you're looking to kill. Although this passive is strong offensively, it does not help you when you're running away.

Tumble

An auto attack reset that also makes you tumble to the direction of your cursor. At max rank, you will be able to tumble every 2 seconds! This is the bread and butter skill of Vayne, which basically makes her extremely flashy with constant repositioning - which gives her the biggest kiting potential out of all the AD carries.

Silver Bolts

Every third auto attack that you hit on the same target consecutively (meaning if you change targets, silver bolts also resets), the target will take a base damage + a % max health true damage. This makes her good ALL-GAME long, and makes her incredibly deadly. This is also the thing that makes her one of the best carries in the game!

Condemn

This ability will knockback a single target, and if it knocks them back against a wall then they get stunned. This is both used as a CC, and as a self peeling ability. This is also what makes her strong against bruisers, because when you're 1v1ing a bruiser and he jumps on you then you can condemn against the wall for a free stun, and if you're well farmed you should easily be able to 1v1 them. If you're incredibly skilled with fast reactions, you can also cancel some skill animations such as Alistar's Headbutt or Shen's taunt by casting this immediately after they start their spells! It's worth mentioning that condemn.

Final Hour

Gives her a flat bonus AD, grants her a short stealth everytime she tumbles, and gives her TRIPLE the movespeed bonus from passive. This ultimate is one of my favorite ultimates, not only do you gain massive AD for free, but you become nearly impossible to escape from. In teamfights, this makes you really really hard to catch without an oracle or a pink ward due to the repositioning from tumble AND the invisibility. Make sure you pop this as early as possible the moment you realize you're committed to fighting. Otherwise, you can also use it as an escape to use final hour + tumble to get away with the invisibility.

Vayne isn't Top Tier in Patch 3.15, but if you master her she can still be a very strong pick!