Vayne is a powerhouse in Dominion. She has amazing synchronizing ability with the newer items, and her 1v1 potential with DPS makes her dangerous to any and everything on the Crystal Scar. So, that being said, here is a guide that explains how I play Vayne on Dominon coupled with the build I use.

On the Crystal Scar, terms like 'Carry' and 'Fighter' just don't apply anymore. So where is Vayne's niche?
Vayne should be, in an ideal scenario, wandering around the middle of the map, just out of view of the outer ring, waiting to pounce (or Tumble) onto unsuspecting enemies. Vayne is a Slayer which means that she is best at taking out enemy champions and preventing any progress from being gained because every time that they try and go for a spot on their own, they get taken down. (for more information about what being a Slayer is about, read Dominion Guide: Roles and Teamwork by Zemiazas.

Marks:
I choose Greater Mark of Desolation because Vayne's usefulness in Dominion is dependent on her ability to do a lot of damage. And while she is capable of doing a lot of damage without any armor penetration thanks to Silver Bolts, it only procs every 3 attacks, and I would rather do consistent damage for every attack. That's not saying that armor pen is the only way to go though. Greater Mark of Attack Speed will allow you to get more early game Silver Bolts procs, which can be devastating. The reason I don't get these however is because of the large amount of Attack Speed items I get in my build.

Seals: I like Greater Seal of Armor. There are tons of viable choices here, but thanks to Dominion's aura, I don't really like getting anything for mana regeneration and Greater Seal of Evasion don't really give a large enough bonus to be worthwhile by themselves.

Glyhs: I chose Greater Glyph of Cooldown Reduction because this to me seems like the best choice of a glyph for Vayne. I've seen a lot of builds prioritize attack speed here, which may be useful in Summoner's Rift where you need something to carry you until you get the gold necessary to buy attack speed, however in Dominion, you get enough gold to make the marginal gain from Greater Glyph of Attack Speed negligible. Another viable choice of Glyphs, if you're looking for a little tankier build, is to get Greater Glyph of Magic Resist for a little bit more MR.

Quintessences: I chose Greater Quintessence of Attack Speed because of the early game attack bonus. This is much more viable in Dominion with Vayne because you start the game with your Silver Bolts, making attack speed early game much more profitable. Another choice would be Greater Quintessence of Desolation. I don't use these in Dominion however because of the aura from the Crystal Scar which gives me 15% armor penetration anyway. So while a smaller amount of flat penetration, like from your marks, is nice; I would rather get the attack speed for these. Although, I will say, it would also be extremely viable to exchange the Marks with the Quintessences. This however is a matter of preference.

I choose to go 24-6-0.
This is used to maximize the damage available to Vayne in her metagame while also allowing her to get a little bit more free durability.
To do this, I take every AD associated mastery as well as overall damage increase in the offense side and Resistance and Hardiness on the Defensive tree.
I choose the Defensive tree over the Utility tree because on the Crystal Scar, the Recall timers are already extremely short, so having a second taken off of it isn't really worth it. You aren't getting any Utility associated masteries, so Summoner's Insight doesn't do anything for you unless you choose Flash over Ghost. Also, death timers are significantly shorter than on Summoner's Rift, so Good Hands isn't as effective and Vayne just doesn't need the mana or mana regeneration. The only thing that she can really benefit from is Swiftness , and that involves too much investment for such a small increase to movement speed.

In this build, I prioritize Tumble over my other skills in most games. The reason for this is because the extra damage from it is large, it allows for dodging skill shots, and the ability to get that last little bit of distance for Silver Bolts is a large advantage. That's not to say that I go this route every game. There are games where the opposing champions are all, or mostly, tankier than normal (i.e. champions like Jax, Nasus, and Olaf). In these cases, I prioritize Silver Bolts with the same importance as Tumble to counter their larger than normal health pool. I always start the game with Condemn. Condemn is a MUCH better skill in Dominion than it ever was in Summoner's Rift. Almost every place on the map is within easy striking and pinning distance of a wall. This allows the utility portion of this skill to be much more viable and much more damaging also. Generally, I don't level Condemn up a whole lot because it's the utility, not the damage, that is the most useful part of this skill and since the stun doesn't increase with level, and it still does take a little bit of skill to pin, I would prefer to take a safer route and add damage to skills that I know I can hit every time.

For Summoner Spells, I choose Exhaust and Ghost:
Exhaust- I like Exhaust because of its utility and because for a 1v1 champion like Vayne, if she can't take down an opponent, than her usefulness to the team is dramatically diminished.
Ghost- I am a big fan of Flash on Summoner's Rift. However, the cooldown on it and the short distance it goes isn't worth the ability to run away, catch up, and race to capture point capability that Ghost provides.

Some other viable Summoner Spells:
Ignite- A DOT that adds a little bit extra to your DPS and reduces their healing so that your teammates can get the kill if you can't is more powerful than most people give credit.
Flash- Still a viable skill in some circumstances. I just think that Ghost is a better ability on the Crystal Scar.
Cleanse- A lot of skirmishes means a lot of CC. If you feel uncomfortable or want to play a more defensive game, then by all means, get this.

To start, I get Prospector's Blade and Boots. The Prospector item gives me some early game health, attack damage, and a little bit of lifesteal. But it doesn't build into anything! I know. But the very first team fight (usually at the Windmill) happens less than 30 seconds after the champs are released, and you're going to want this little bit of extra umph to get you through (remember; shorter, faster paced game than Classic Summoner's Rift which means that items that give benefits sooner are better).

Next I get Berserker's Greaves. These give me a decent bit of cheap attack speed to proc Silver Bolts more often. Mercury's Treads are a good choice in games where you know that there's going to be a lot of CC. And if you don't feel fast enough, get Boots of Swiftness.

Kitae's Bloodrazor and Ionic Spark: Examine the other team for a second and ask these 2 question. 1) Is they're main damage dealer a brawler with a lot of HP like Olaf or Jax and 2) Do they have more than 3 characters that aren't 'squishy'. If the answer to either of these 2 questions is 'Yes', then get Kitae's Bloodrazor next. If not, then get Ionic Spark. After you got your 3rd item, work on the one that you didn't get. This will turn you into the DPS machine to fear.

Entropy: This is like the Frozen Mallet for Dominion, but it's better. Why? It has an active, and a really good one at that. It passively gives a 35% chance to slow, but upon activation, the chance is increased to 100% and your attacks start to do true damage. This is like procing Silver Bolts for flat damage every single time you attack. Want to turn the tables in a fight real fast? Activate Entropy.
Tip* I always put this item in the same slot every game. For instance, I always put it in my number 2 slot, so that no matter what, I know where it is.

My last item is situational. For ideas, read the next section.

Sanguine Blade- This is the most common item that I get 6th because it's the Dominion equivalent of Bloodthirster. A decent bit of damage on top of stackable lifesteal increases the chance I have at coming out on top of a fight as well as increasing my sustain in teamfights.

Phantom Dancer- This item gives critical strike, movement speed, and attack speed. All of these things are useful for Vayne and the price isn't so far out there as to be completely beyond the realm of conceivability in Dominion.


The Lightbringer- This is an item that's great for chasing or killing enemies with stealth and therefore should only be taken if you're having trouble fulfilling this purpose (like battling Twitch, Evelynn, or Shaco).

Vayne is best in Dominion when she can take down enemies quickly. While this may not directly influence the rate that you get capture points, having a key member of the opposite team dead for a teamfight, or having them unable to cross the jungle to get at one of your own capture points is an extremely valuable weapon in a game where time is the biggest threat you have. Remember, you only have to be winning by 1.

A significant part to playing Vayne is knowing when to attack, and when to back off. She is an assassin, so definitely go into kill an enemy, but don't valiantly hold out against 3 or 4 of them. She doesn't have the durability to buy your team any real time to get to the defense and there's no way that she can hold off that many at once. In the end, you're better to your team alive. Learning when to engage will dramatically increase your score and ensure your importance to the team for the whole game.

The following is a little explanation as to how I use each individual skill in Dominion. Some of the techniques are similar to Summoner's Rift, some have a slight twist to them. You start the game with access to all 3 starting abilities, so knowing when and how to use them in tandem will increase your effectiveness and score while earning you a lot more kills.

Tumble is a very powerful move that will increase your damage by a significant amount. A Tumble can get you just out of the way of a skill shot that would otherwise do a large amount of damage, help you catch up to an enemy to get another hit (and that last Silver Bolt, and it's a large part of your combo and a significant reason why Vayne is such a power house. Remember, Tumble resets your attack timer.
Use Tumble in combination with basic attacks to maximize damage or use it to get quickly into bushes. Enemies still can't see you in there, that hasn't changed from Summoner's Rift. The difference however is that while it still breaks the locks from skills and basic attacks, they are also more often than not conveniently placed near a wall; perfect for a Condemn stun and a complete turn around.

Not much to say here. The 3rd hit is the most important, so make sure you get it. Tumble and Night Hunter will help you with that.
In team fights, hitting one enemy 3 times will do a significant amount of damage. But this leaves you with a dilemna. The close quarters fighting of Dominion is not like the spread out, mobile fighting of Summoner's Rift where the only real way to get a kill is to focus one enemy down while they're around. Dominion is much more team orientated, and so sometimes being a team player is more important than getting the kill. So how do I help? Getting 3 hits on an enemy, then switching targets to hit another 3 more times spreads out the damage, allowing some of the other champs around you with AOEs and and tanks with CC to mop up and win the teamfight.
But why change strategies? Well, let's say we don't and we go ahead and take down this one enemy. That leaves 3 or 4 more around you, and they're all just as fed as you. And let me tell you, they're not going to be focusing the tank. Switching the targets increases the chance that one or more enemy will back off, or it increases the chance that more than just that enemy will fall thanks to your team. ALWAYS COUNT ON YOUR TEAM FOR AT LEAST 2 KILLS.

This skill is several times more useful in Dominion than it ever was in Summoner's Rift. This skill is nearly always in range of something to pin the target to, increasing the chances of you getting the extra damage boost, and more importantly, the stun. THE STUN WILL SAVE YOU FROM CERTAIN DEATH ALMOST EVERY SINGLE TIME. Fighting 1v1? Condemn to a wall, Tumble attack, attack Silver Bolts combined with your Kitae's Bloodrazor and Ionic Spark. You just turned the tables. Not sure if you can finish the fight? Condemn stun and run. There's no shame. Just be sure to ping so that your team knows there's somebody there.
Another useful thing of note is that even if you don't hit a wall, it's still a knockback. Use this to knock people off of your capture point or to help out a teammate in trouble. You may walk out with a kill and a 'Thnx' from your teammate.
Note* Condemn applies a tick towards procing Silver Bolts...

This is probably the best offensive steroid in the game. I use this when I know that the next fight is going to be rough, like when I'm going up against another Slayer, or when I'm going into a teamfight. This is also a useful skill for the slight stealth it gives with Tumble. This is fun to get that last bit of distance from the Fog of War to catch an unsuspecting enemy by surprise.
It's also good for running. Activate Final Hour and then use Tumble into a bush. Turn around use Condemn to pin the enemy into a wall and continuing running or finish the fight.

This is one of the very first guides for Dominion, so there is bound to be some new strategy or some bit that will eventually come out or that someone will come up with. I'll try and keep and eye out for that and will be upgrading the guide accordingly.
Meanwhile, any comments or questions that you have are more than welcome. I just ask that any comments that you do make are explained and please don't downvote based on only one part of the guide and, if you do, please explain the reasoning behind it.
Mobafire is, in my opinion, not a competition to see who has the best guide, but a way to compare playstyles and guides to try and learn something. Not commenting on what you thought was wrong denys me and other players this chance.
That being said, thanks for reading this guide and good luck on the Crystal Scar!