Starting phase
I recommend to start with a
and a

Second phase
Philosopher's Stone and

Third phase
and

Fourth phase
and

end phase
+ +
In the end phase you need to decide for yourself which item you prefer first.
if you really have to fulfill the role of "tanker" get yourself a warmog armor first.
At the moment you need space: Sell Philosopher's Stone

NOTE:
The time intervals i call "phases" are just times when i usually (can) go back to get these.
a phase can be very early or be very late. Of course when you can buy parts for a later phase. buy them!

EXTRA NOTE:
Sometimes i skip , if the enemy is a heavy magic team.
Instead get something u feel fine with, perhaps: ?

EXTRA EXTRA NOTE:
Wards > RULEZ!
Sight Ward

Early sustain.

Philosopher's Stone
This is a nice item you can keep till late game. it really gives nice HP+MP regeneration.
usually you wont be OOM with this. and with Heart of Gold it gives 1 gold each seconds


This + passive = godlike, nice anti-CC


About this and Randuin's Omen some matches it just doesn't feel right. then i just skip this item. Overall decent hp. and with Philosopher's Stone it gives 1 gold each seconds


This is really a boost for your Bladesurge and its needed for Trinity Force anyways.


This item is really nice, it gives everything you want.
NEVER SKIP THIS!


Ah this is the item i think is least important, though it gives Hp,Armor,health regeneration. and the active is nice (You slow the enemy movement+attack speed for like 3 seconds for about 40% (Depends on your armor/magic resistance))
Just get this if you feel like, else just buy the other items first.


Dmg,Dmg,Dmg it gives some nice damage + crit, though if u never die. you could get a Bloodthirster cuz it can gives +100 attack and some nice chunk of lifesteal.


Hp,Hp,Hp remember you're a offtank.


When you never die and you think u got enough hp, then u could get this.
it gives some nice Movement speed in combination with Trinity Force.
and gives some nice crit in combination with Infinity Edge

IONIAN FERVOR
This with mercury thread boots is really anti CC, nice team fight passive.


BLADESURGE
This is a very nice minion last hitter, because you refund a part of the used mana + Cdt refreshes.(Only if u kill the target)
I use it in combination with flash to chase enemy's down.


HITEN STYLE
The key to Irelia's high sustain. I max this skills last because i simply think the other skills are more useful.


EQUILIBRIUM STRIKE
This skill is a life saver!:O, When you're at lower HP% then your enemy you stun the target for freaking 2 seconds :>.you can use it to escape or to tear your enemy apart.


TRANSCENDENT BLADES
This ulti gives you high sustain aswell. and it can be used to kill fleeing enemy's.
besides the CDT is very short at lvl6 its 60 seconds. but when I'm about 18 its like 30 seconds.

For the summoner spells i took:
+
This are just my standard choices for DPS champions.

OPTIONAL:

Exhaust
You could get this if you want, its really nice as well.


Ghost
you can use ghost to flee or chase enemy's down. But i rather use Flash because flash is sudden, so its easier to catch your enemy's off-guard.


Smite
Of course get this as jungle Irelia :>

Really don't get this!

Revive
Srs?! are you noob?


Clairvoyance
Leave this to your Tank/Support


Clarity
Irelia doesn't have a big mana problem.


Cleanse
You're Irelia your passive gives 40%, your boots gives 35% (It doesn't work like 40+35=75)


Heal
What are you talking about? Irelia got a high sustain herself.


Rally
Again leave this to your Tank/support


Teleport
I think this is a Mwah Spell, I can be useful to backdoor or gank.
But i rather take some offensive/defensive spells you can use in fights.

(Seal of Resilience +1.41 Armor)(9*1.41= +13armor)
Great Armor early game! goes great with Irelia's high sustain.


(Seal of Resilience +1.49 Mag.res)(9*1.49= +13Mag.res)
Great MagicResistance early game! goes great with Irelia's high sustain.

Greater Quintessence of Desolation
(Quintessence of Desolation +3.33 Arm.pen)(3*3.33= +10Arm.pen)
Irelia might be a high sustain champ, but that doesn't mean she don't need damage.
Armour penetration is in my opinion the best "DPS increase rune"

Greater Mark of Desolation
(Mark of Desolation +1.66 arm.pen)(9*1.66= +15Arm.pen)
Irelia might be a high sustain champ, but that doesn't mean she don't need damage.
Armour penetration is in my opinion the best "DPS increase rune"

NOTE:
For seals/Glyphs I'm taking flat runes because you need them early/mid game, Late game you got items to depend on.

The opinion of masteries are really split.
Thats why i just took a random masterie(21/6/3)
Seriously just go for what u feel like is the best.
go (21/x/x) for more DPS
go (x/21/x) for more DEF
go (9/0/21) for more CDT? (i don't think u really want that)

PROS:
+High sustain (W + R)
+Stun/slow (E)
+WTH she can't be slowed!? (Anti CC)(+Reasonable speed)
+She is a girl :D (QWER)


CONS:
-Vulnerable to range champs
-If you can't farm then u can't play
-It's annoying to use Transcendent Blades while running away.
-Melee

Heey,

This is one of my first builds.
Maybe it ain't the best build/guide, but this are my personal preferences and i want to share them with you guys.

Irelia:
How longer the match takes, the stronger Irelia gets. (it's kinda obvious but I'm just saying :>)
Depending on your laning enemy('s)(and maybe laning ally) it can be a pain in the *** early game. but don't worry just endure it, it will be all better late game.
one thing. DONT FEED (if you feed with Irelia then u are just a lametard)

NOTE:
My introduction ain't important, i don't like introductions. Introductions are boring.
thats why put this at the end! :D

NOTENOTE:
I tried to keep my guide short, and didn't use pictures and tried not use to much text.