Mordekaiser Botlane is the answer to Vayne

Mordekaiser botlane heavy counters Vayne.

1. She is not one of those ad carry able to abuse the morde low range capabilities in the early game due to their terrible handicap on pushing. He will just put w on minions or his support and permashove the lane with no answer and no counterplay.

2. Vayne outscales Mordekaiser LATER than how she outscales the normal ad carries. AND Mordekaiser should not have any late scaling problem because he doesn't want the game to last over 30-35 minutes.

3. You can rush Tabi Thornmail before she closes her first item. Hitting you would just help you kill her. THIS will also make you laugh at any Rengar Kha Zix ( and all other assassins AD ) junglers who will DEFINETELY gank your lane when it's pushed.

4. Vayne can abuse her ultimate invisibility a lot LESS, because Mordekaiser ult on Vayne causes her to perma " shimmer " ( if you don't know what shimmer effect is, read the patch notes of 6.22, unless you wont understand ) for 10 seconds, so even if unattackable by target-spells, she can still be AOE'd and SkillShott'd

5. Even if she gets fed because of jungler camping and top teleporting each time you fucking engage their bottom, you will always be able to kill her. ( I mean: 0/5 Morde STILL OUTKILLS 5/0 vayne ) And if, for little mistake, you get her ghost, the teamfight is over. You will 3shot any squishy and your shield will be like perma re-filled. You can even do towers without minions when you have the vayne ghost on your backs.

You may not belive me but that's the truth. In the past month when vayne was not particularly in meta I had a hard hard hard time reaching diamond as Mordekaiser, and I failed on that. Today I just rushed 8-10 games as Mordekaiser Bottom and told my mates NOT TO BAN the vayne: It resulted playing against her 7 times out of 8. I won all games and went diamond in a blink of an eye.

Hope this helps.