The problems vayne has

She is really toxic to melees but well that is a very know fact and she is on par with kalista on that she counters tanks so much with an uncountarable damage and mobility BUT she has mobility and movement speed boost coupled with an ad boost which makes her a really good assassin with invisibility as well so she counters tanks while being an assassin as well her early game with that passive means you can't escape from her and once she is ahead you can't do nothing about it she escape from ganks pretty well so unlike her friends she hasn't a weak early game because she has enough damage to duel and enough mobility to escape from an engage or a gank PLUS HER MID GAME is really stroooong when the enemy need damage items for deal the same amount of damage she can deal with a botrk plus life steal runes resolves a lot of her problems