"Vayne. Just buy thorn-mail and she becomes useless. She's incredibly squishy but you can't run away from her easily so it's best to just hit her hard and get her to panic."
Because Thornmail negates True Damage?
Vayne doesn't need many items to do good damage, the best way to counter her is not over extend. In any organised Ranked, she will either be insta-banned, or 2nd picked.
Also, I only see value in Ori for support, her shield with AP is good, and she plays well with aura items.