Say hello to Irelia one of the hardest hitting champions in the game. With a price tag at 6300 (IP) I was hesitant to first play her. When she was featured in the free week rotation I decided to give her a shot and needless to say I fell in love. There are several ways to build Irelia, but as the current metagame favors the "tanky DPS" characters, I will show you a "tanky DPS" build that works extremely well with Irelia.

For Runes I chose the following :

ArmPen Reds are almost a necessity on any DPS character. Makes her auto attacks hit that much harder and negates innate armor

HP Yellows : I juggled around HP and Armor Yellow Runes, and both work very well, but for Irelia I would much rather have a larger health pool to begin with. Just a personal preference as both armor and HP yellows work very well

Magic Resist Blues : most cost efficiant and I run them on any DPS character.

HP Quints : Again I like to build Irelia beefy, not really "resist-y". I find that HP quints help me early game a lot more than any other quints

0/21/9 for any defensive character. Gives bonus armor, magic resist and HP.
The 9 in the utility slot is just for improved ghost and a bonus XP (thank you Mastarwe for the helpful tip!)

I consider only two items to be "must buys" on Irelia, TriForce and Merc Threads.
Merc Threads combined with Irelia's Passive will negate almost any or all CC aimed towards Irelia.
The Triforce combines everything that Irelia NEEDS into one nifty package. Sheen Procs after bladesurge/Equilibrium Strike, Phage slows, Zeal movespeed, Bonus HP/Mana pool. You couldnt ask for more.

So to start the game I start with a Longsword and a health pot. I like to rush the Phage aspect of the TriForce first, as it gives a nice HP and AD boost. After Phage buy boots, and if you can get Merc Threads even better. The CC reduction on the Merc Threads works very well with Irelia's passive.

Lane a little longer, farm up and buy a sheen. From here on out you should try and stay in lane until you can buy your TriForce. Roam around and gank lanes, pressure buffs and kill dragon. With your passive lifesteal and ultimate you should be able to stay out in the field much longer than a normal champ.

Once TriForce is finished... so is your build for the most part xD But since you have 4 item slots left might as well fill them in.

Your next objective is the Frozen Mallet. With an even larger HP pool than TriForce as well as a guaranteed slow, the Frozen mallet is the king of soft CC. activated with Hiten Style, you can make sure nobody will be getting away from you.

From there banshee's veil is a great choice. Protip: Banshee's Veil should be built on every champ ALWAYS. Sacrifice one item slot for some survivability, and in Irelia's case, it works very well. More MR as well as a bonus HP pool that will synergize with ..

Atmas. By now Irelia should be sitting on an HP pool at around 3000. Sup 60 Attack Damage. Also gives armor and crit chance. So much win

Now the final item is very situational and I like to juggle around three different options.

For a beefy team I like to build Madreds. Gives armor, attack speed and attack damage. And the passive on Madreds MELTS tanks. Combine this with your Hiten style and watch tanks melt

For a Magic Heavy team I like to build Force of nature. Insane HP regeneration as well as a huge MR boost.

For an Attack Damage heavy team (carry heavy team) I choose either Frozen Heart or Thornmail. When there is an Ashe/Caitlyn/Trist or any other carry that relies on attack speed I choose Frozen heart. (its aura slows attack speed) If there are crit heavy champs (gangplank, yi, tryndamere) I choose Thornmail

I like to balance out my skills but I put a slight preference on Hiten Style. The passive lifesteal is just sooo good during the laning phase. Other than that, I get one point in bladesurge (i mainly use it to dash into enemy opponents) and try and finish equilibrium strike.

R > W > E > Q

I run Ghost/Ignite on Irelia.

Ghost is just a really versatile spell. Can be used to chase down enemies (or get in range for you Q) or get away from one.

Ignite is for those annoying healing characters like swain, nunu, mundo.. Also a great way to ensure a kill early game. When you see that enemy sitting on a bar of HP left, autoattack and stick ignite on him and retreat. "you have slain and enemy" xD

Irelia is probably one of the toughest characters to bring down in a teamfights. Insane burst, lifesteal like a champ and survivability like a tank. Especially in the current metagame that favors the "tanky DPS" characters, Irelia shines.

but remember Irelia's main objective in teamfights is to bring enemy carries down. With this build you should be able to dash in, burst that enemy carry down and survive enough to deal some damage to the rest of their team. Q into the face of the carry, wait for the sheen proc to kick in, activate E to slow the carry, active W and start WHALING on that poor ashe/cait/trist. When you see your health bars getting dangerously low, heal yourself with your ultimate on some poor unsuspecting minion wave and dash right back in.