User blog comment:ClariS/Unofficial PBE Patch Notes (148)/@comment-218.186.15.10-20120916111222/@comment-79.175.93.216-20120917225013

Vayne is a kind of champion that will kill somebody in 1 shot or will die from one shot. She is really strong now in the means of damage output, in the means of defenses and health, even Soraka has better stats.

Her tumble grants her a percentual boost to next auto attack. So when she uses it she will deal 150% of her damage. Put critical strike in this formula and it will deal a lot of damage. If you buff it, then it would be way more powerful.

In my opinion stats that would be good to buff for Vayne and not spoil the ballance would be her range of auto attacks, maybe a slight cooldown reduction on her ultimate and some minor tweaks.

Since her defenses are soo low her range should be buffed so you can compete with other carries that now have the same range as Vayne but have way bigger defenses. Graves can reach 100 armor with no sweat while you need to sacrifice a slot in your inventory or runes for more defenses.

She is strong but when Soraka sneezes she dies. I think that is the interesting part about vayne, keep her alive and you get a tremendous satisfaction.