Dominion is fairly new so this guide won't be perfect but its a base for new people to start with. Comments are very much accepted and alternative item builds are appreciated.

I found dominion needs a bit my defense so Armour and magic resistance as well as flat health quint are handy. However, you could change these to suit yourself if you can find a better combo.

I also put in some speed quint because speed is essential in dominion.

Fairly standard utility tree for Irelia with quickness for some more speed.

Irelia can capture any point at the start but I recommend going top or middle. I feel bottom wastes the potential of irelia. She is a off tank and she can handle roaming around.

1) Start always with a sheen, its a great item for Irelia because it activates with her Q.

2) after capturing the windmill you should have a few secounds before the enemy re engages so teleport back and buy Berserkers greave or boots of swiftness. I choose a rune and a mastery path focused on base movement so I would suggest to build Berserkers greaves.

3) after boots ALWAYS build the triforce. Before you get triforce irelia can be a little weak . However, after triforce irelia becomes unstoppable. wont get into if to get phage or zeal first it's situational.

4) Now if you are going against a team with a lot of attack damage get randuin's omen first.
However, if you are going against a team with magic damage get spirit visage.

5) The above items are your core items it provides Defense and offense.

6) the next items are optional and situational , the ones I recommend I have found to be very good on irelia.

--- kitae's bloodrazor
attack speed is perfect with hiten style , extra damage and suffers 2.5% of enemies health.
Great against tanks

--- sanguine blade
extra life steal and even more damage .

--- Guardian angle
if you really need more defense this will give it to you. However, I suggest you grab something in the attack group.

I have seen a lot of bad and good players at dominion and this is just a few tips I think make a effective game.

1 )focus on capturing and holding 3 points, remember you only need more than the other team for there nexus health to go down.

2) stay by the tower and avoid initiating fights away from the tower. The tower is almost equivalent to a champion so having that can make a 2v1 fight into a 2v2.

3) Only go for a 4th or 5th capture after the enemy team tried to take a point you were on and they all died. Then you can over extend however, don't be willing to die for a 4th point.

MUST FOLLOW RULES

avoid at all costs capturing the two points near the enemies base. These points are easy to recapture and if you die due to trying to capture one of these points it will make it twice as easy for the enemy to capture more points.

if you are defending mid or bot near your base don't be afraid to go back to base if you are low on health or have gold.

---dont forget about mid buff this should go to in order of importance stealth burst damage champs such as evelyn , twitch or shaco. Then regular burst damage such as akali but the middle buff can be good for anyone.