No real discusion about vayne, the way i look at it; vayne is the ultimate tank killer. You can change some of the masteries around depending on who you are facing, but this is usually good for when you are vs. lots of tanks.

Pros: Vayne rocks at tank killing. She is very fast and very strong.

Cons: She is more of a late gamer, and she is squishy at beginning.

Vayne is not much of a defender in dominion, but she is a great offense.

First i rush out with Ionian boots, because in dominion your first item should always be boots. The boots give less time to vaynes cooldowns which really helps because some of her spells take awhile to cooldown and its a faster kill for tanks :D.

Next i go straight into phantom dancers which is an awful mistake to rush into, IF you are doing normal 5 v 5, this is dominion and its good to rush into especially with vayne.

I definitly go with infinity edge because that critical strike is very important to vayne, its her best offense against tanks.

Then i go with phantom Dancers again because vayne needs some attack speed.

Randuim's omen i usually go with because they got rid of banshee's veil in dominion and its the next best thing.

Finally, i go with Sanguines blade because i love lifesteal and vayne uses it so well. Also bloodthirsters isnt in dominion either so its the next best thing just like Randuim's Omen.

Some problems that i have to say are porbably the masteries, i went a little overboard on the critical strike, but its fun lol. If you want you can get more attack speed runes so that you can get something other than 2 phantom dancers. You can also get some different varieties of runes instead of all offense, but like i said vayne is the best offense.