Irelia have very easy farming becouse of her Transcendent Blades , and she have great sustain so she don't need back to base so don't waste many creeps. When ur farming in early u can try to hitting ur enemy, he can't attack u, becouse if he do he lose his gold from minions and u just use Transcendent Blades , and get next creep. Ofc don't attack ur enemy in his creep becouse in early game 6 enemy minions will deal more damage then you.
If u feel that ur gonna lose any last hit u can use Equilibrium Strike but try to not doing that becouse it costs mana and u have no protect from ganks. Farming with Hiten Style is mostly very bad even if u are low hp ur Hiten Style don't give u that much to use it + ofc u are loosing ur mana what can even kill u in next trade + cd ofc, ur life steal is enought with this build +10 hp per every shot is too low to use it, mostly if u have basicly 30.

Bladesurge is very interesing abillity becouse we can use that again with no cooldown if we last hit, so if u last hitted the minion u don't have any CD for this skill, it also stack with ur Trinity Force so u can do really nice combos with that abillity, like sick escapes or great bait.

Hiten Style is seriously my favourite spell in the game, yes silmle auto attack buff, it's such a amzing when u are looking at 200 Armor enemy getting big damage from u becouse u don't care about his armor xD, it giving life steal when u are last hitting, it making every trade win, it is just AMAZING how good is that spell

Equilibrium Strike is the only one CC in Irelia, that's really sad but this CC at lvl 13 have really little cooldown and it's really long 2 sec, that's bad that if u have more % hp then ur enemy u just slow him so,he can flash or jump away, but anyway it's not bad.

Transcendent Blades well I think ultimate abillity Irelia is a bit weak but I really like it so much Ohh Irony.... xD. Well ofc that's not totally sucks as i said before it can make really good combo with ignite or if ur enemy flahs away from u u can easy kill him with ur ult or when ur tower is only 300 HP u can just use ur ultimate to save tower and heal yourself

Ionian Fervor Well theres nothink diffrent to say then only BETTER NERF THIS ****. Passive Irelia is seriously Epic, if u have also Anti CC Boots in team fights for example insted of got fear from fiddle for 3 sec u have it jsut for 0.75 sec, it's really AMAZING stuns for 1 sec are 0.25 sec don't u think that's OP? Ofc in 1v1 fights it works worse but it's still really good, i think one of the best passives in the game.

Flash is very importent for irelia, this spell can save ur *** many many time, if u have no escape u just use ur flash and u are safety, it can give u kill also, and ofc u can easier sit on enemy AD Carry in team fights, and just tell him GOODBYE :)

Ignite is seriously epic for Irelia, u can very easy get First Blood, becouse of that spell and also in late game it can be epic combo with ur ultimate, u jsut use ultimate 4 times and igntie and enemy lose so much HP, and u don't even need 1 shot for this.

Ghost is a bit like flash, but u can't go over the wall, but u can kill enemy easier then if u have flash becouse if u flash, u are still slower and still not aatcking, just running for enemy, if u have ghost u are faster so u can run and attacking insted of run only and doing nothink, bot works worse in late so i think mostly flash is better.

Teleport is very interesing spell for Irelia, u can easy help ur bottom lane, and also quick back for some items rest some health and back to ur lane with Hp and items, while ur enemy is still with out it, but if u need to pay ignite for teleport, better don't do hat becouse i think ignite is rly awesome for Irelia, TP is for more tanky champions.

Most importent items

This item is very strong in early game, u can use that to slow enemy and kill him, giving u epic sustain with w dorans and life steal and u can build Blade of the Ruined King from that item.

This items is very very nice it give you HP, AD, it's very importent for Irelia nad ofc great passive witch works like ghost, so u have 3 summoner spells xD.

Many people build this item 1st and sstarts from shen, I think that totally not work becouse shen gives u nothink, only mana and AP so useless a bit for Irelia and it have big price and trinity alone give u almost nothink so i think good item for Irelia but for sure not first and not shen is most importent in that.

This item is really awesome if u have that + Phage + Ignite + Transcendent Blades+ Blade of the Ruined King u have really epic Wombo Combo, and nobody can fight u alone.

I like those Runes becouse it help me to do quick first blood, and making my Damage seriously very nice. It is not that good in late game, but i still like to have it easy own top and insted of better late game runes i just have better items :P.

Attack Speed is much more effective in late game becouse with maxed Hiten Style and ur AD u deal really good damage,but faster with this runes.
greater mark of armor penetrationgreater Quintessence of armor penetration
Those runes ofc u take vs very tanky team becouse even with ur W, the damage is low, but this runes u take ONLY SOMETIMES i think u should take this runes once per 200 games, rly extreamlly situational like Rammus jungle, Leona support, Malphite top, Urgot AD Carry and Ryze Mid.

Pros - easy farming - hard to counter - True Damage - Pro sustain - Tons of Damage - Can LF after every trade - Low CC

Cons - Squishy - Weak AoE `

Irelia is not as strong at team fights as split pushing, if one person try to stop ur push and all others stay u can try to kill him and as Irelia u can mostly easy do that, if 2 people try to stop u , ur team can easy fight 4v3 or push or take dragon/baron, and u even if u are skilled or fed or ur enemies are unskileld or "unfed" u can even kill them both becouse Irelia is that storng that u jsut stun one of them use combo and is almost dead or even dead and 2nd u can easy kill auto attack+ ur skills have low CD so u can wait for skils and kill that guy.So If u can better try to split push then go to fight in my opion becouse irelia doing it really good.

Thank you so much for enjoy my guide for Irelia and i hope it will give u so much fun to play her as this guide, so GL & HF.