for this build i just wanna say the i haven't played a lot with this champ but i realy like it. i tested many builds and many items with irelia and this is my build at the moment.plz read the hole guide before comenting.

for my runes i go with armor penetration marks, armor seals, magic resist glyph and movement speed quintessences. you can anso go with armor penetration quintessences, cooldown reduction glyph and flat mana regen seals.i prefer having movement quintessences to chase because if the dude is out of range theres nothing u can do... i like running faster than him.(450 movement speed or 500 with sword of the occult stacked).for the glyph and seals i just wanna say that my build is more tanky than dmg so its nice to be tanky early game too.

for my masteries i go with 0-9-21 some goes with 9-0-21 and i have to admit i realy dont know why. the 9 in defence is way more usefull then in offences.and i prefer having 21 in utilities cause of the movement speed and the cooldown reduction.

for my build i start with 2 health potion and a sapphire cristal. i tried with a doran shield and i did a realy bad early game but its another option.then i go with my boots becasue its realy usefull to have massive movement speed early game.once i get enough money i go back and rush my shen because without it, my irelia build is ****.if game goes well, im gueting sword of the occult(if u dont like stacking items rush direcly the trinity force and for last item get an offencive item like youmuus ghostblade, black cleaver, maldread bloodrazor or frozen malet can be good too.)then im rushing phage to get trinity force with is a must for my build.then im always building depending on the team if i need magic resist first i get banshee if i realy need lot of magic resist i go with force of nature instead of banshee. if i need def i go with randuins if the other team is mostly runners/ap build or i go with frozen heart.then i go with guardian angel. i dont know why... but irelia is the onlee champ i like having guardian angel it saved my life like crazy i think i never died once i get it.
PS:quicksilver sash can always be usefull

if you are about to gank or kill a noob backdooring, you first want to hide in bush (dah) and wait for the best moment to charge it. one hes in your range(or so) use your q and e he will probably want to run, if not then you are being understimate take adventage of this, be sure to have his minion behind him so ur ult will heal on minions too and you should get the kill.if he runs you have to care on the attacks you do. he need to be slowed the hole time you are attacking it. so once your e slow(or stunt) is done, use randuin(if you have it), and then use exaust.in this case he will always be slowed. you need this slow to cast your ult! because you will ult and then shen then ult...if hes not slowed, our aa(auto attack) wont hit!

to make it simple during the hole gank you need him to be slowed by any way and u wanna:
q-e-aa-w-aa-r-aa-r-aa-r-aa-r-aa-r-aa

for my summoner spell im using flash for sure and the other always depend on the team.if we dont have any teleport i use it as second spell. if we dont have ignite im using it. if we have enough ignite and we got a teleport, im going with exaust. i love this sumoner spell because or the slow let me chase the champ and hit every hit of my ult/shen combo.these are all good spell that can be usefull in some situation. you can't know hwo the game will goes so its a guess.if its ranked its easier to chose ur sumoner spell. if theres a yi/shaco/teemo/eve/twich, rush teleport cause they might backdoor. if they got swain/vlad/warwick/dr. mundo go with ignite even if the hole team have it.if not, go with exaust and in team fights, be sure to exaust the right champ. nunu/katarina/malzahar/kennen are nice champions to exaust.

Pro

-great farmer
-great dps
-tanky
-REALY understimated 1v1
-makes ranged carry useless
-not the first target in teamfights


Con

-no ranged attacks to harass
-low dmg without shen

ok first you are quite tanky but you are not the initiator of the team. initiate cause you will be the first target and you wont be able to help your team enough.a alistar/amumu/rammus and other tanks are here to initiate let them do tier job.once the teamfight starts, charge direcly on the ad ranged carry or another fed carry.the carry will keep run off and try to avoid you wile some of them attack you. your tanky build makes you able to get this carry and get off safely without any problems. be sure to always keep an eye on your life. you might be in the midle of the teamfight so once you see your life go down fast flash out and run, you did everything you can do.