Hello,
I'm MisterL2 and this is my first guide, I will edit this guide and it is still all WIP.
I am Diamond I.

Vayne is a strong lategamer with a very weak early game but exceptional outplay skills especially with blade of the ruined king. In total, Vayne got the most amazing mechanics in the game. This makes her hard to play but also very very strong for 1v1 situations, lanefights and enables the outplays that Vayne is so famous for.

Her passive allows her to chase. That's it. Keep chasing.

Vayne's main ability is her Tumble as it allows for a very long stealth time in combination with ultimate and makes her the least vulnerable ad carry in lategame teamfights. She also benefits a little from blue buff due to the cooldownreduction. 0.2 Seconds might not seem that much, but if your cooldown decreases from 1.6 > 1.4 and you have 1 second of stealth, that removes a third of the time that you are visible during your ultimate.

Her Silver Bolts are a very strong lategame skill against tanks and therefore should be maxed secondly.

Her Condem is strong for early game lanefights and lategame 1v1 situations and therefore it is clever to take a point in it early to get the stun, but there is no need to max it fast for the little damage and cooldown reduction bonus. You should not spam this skill in laning phase due to the high mana cost. Only use it if you can cause a stun or to escape a potentially dangerous situation.

Her Final Hour allows for extra damage and enables the stealth for the Q while tripling the bonus movement speed from her passive. It has 3 purposes:

1) To escape using the stealth / Survive in a teamfight
2) To deal additional damage (Teamfights or rarely: Splitpushing, more tower damage)
3) Chasing: You have +60 movement speed from your ult if you chase, causing a total of +90 movement speed buff in total (30 from passive, tripled).

Vayne has 3 main problems:



Caitlyn:

She outranges you with her autoattacks and her Q and finishes you off with your ult. Her traps prevent your stealth. Additionally, she is a strong lategamer and only a little weaker than Vayne in the lategame, so you need to get money from somewhere. Doing the golems is a good way.

She has 3 main problems (yes, I like the number 3):

1) Her autoattack range of 650 is 100 higher than Vayne's.
2) Her Q has a huge range and deals alot of harass damage.
3) Vayne has no means of blocking or resisting Caitlyn's ultimate other than a very unrealistic Condemn (You'll never be in range or fast enough to do so unless Caitlyn is very stupid).

To counter this:

1) Stay back, only go forward to lasthit as late as possible and use tumble to move in and out quickly.
2) Use your Tumble to dodge her Piltover Peacemaker. Remember: Her Piltover Peacemaker costs alot more mana and has a channel time long enough for you to react.
3) Watch that you never fall low and make sure you have a tanky Leona / Blitzcrank support to protect you in case of emergency. Both of those have some type or shield.

Draaaaaaaaaven

Is by far her biggest problem.
There are only 2 problems with him though:

1) Huge damage and DOT with Spinning Axe.
2) His E prevents any chasing or silver-bolt-harass.

To counter this:

1) Buy at least two Dorans, sometimes even three. You can chose whether to start with Dorans or a Long Sword + 2 HP Pots in this case, but you really need 2-3 Dorans to survive the early game. Trust me, it pays off.
2) This one is hard to counter: A well-timed flash can jump OVER his E. This requires very good reactions though.

Varus

Varus might not be the most dangerous early-gamer for the first few levels if you stay passive and dodge his skillshots, but once he hits lvl 6 there is a big threat. Another problem is, that Varus does not fall off in lategame like Draven, so you need to farm well in the laning phase.

He has 3 problems (once again):

1) Skillshot ( Piercing Arrow) harass
2) Alot of harass damage with W + Passive
3) Ultimate prevents stealth (Very dangerous!)

To counter this:

1) Dodge with your Tumble
2) Stay back and once again only attack creeps if you can no longer wait. Do NOT fight with him before level 9 or 11 EVER.
3) You MUST take cleanse against Varus, otherwise his ultimate is an instant death sentence. You can try to dodge it with Q (which is very difficult) or with flash, though cleanse is safer.

Well, this is very simple: Anything that gives an attackspeed buff and is possibly a little tanky to protect her.

Examples of good supports:
Leona
Nunu
Nidalee (that maxes E)
Taric (tanky + sustain + resistance for vayne)

OK supports:
Nidalee (that maxes Q)
Janna
Blitzcrank

Bad supports:
Soraka (Vayne doesn't need mana, Soraka is not tanky)

Vayne is strong in lategame and bad in earlygame. Is that it?

Pro's:

Strongest Lategame Damage
Almost permanent Stealth
Can 1v1 any Champion at Level 9 / 11, even a Draven
Huge kill potential through her Condemn.
Chase potential through passive
Decent ganks using Stealth
Lategame tank bursting with silver bolts + Botrk
VERY fast early dragons with silver bolts + Botrk and attack speed buffs from supporters.

Con's

Very weak early game
Easily bullied out of lane
Vulnerable to ganks without ultimate or on low levels of Tumble.
Little escape skills
Squishy early game (alright: an adc)
Easy to focus due to low autoattack range (excellent use of stealth needed!)
Easily loses potential if unable to chase successfully (Draven, Nidalee)

I hope I haven't done to bad and I will edit this guide later on and I would appreciate any constructive advice as of how to improve.

Vayne is a weak early game champion with a low autoattack range, but good chasing skills, good self defence, very strong 1v1 potential and probably the highest lvl 18 Damage (together with twitch) and for sure the highest tank-shredding ever. True %hp damage is all you need.

MisterL2

PS: Ashe doesn't counter Vayne. No, really! She's useless if you avoid her Volley.