Pros:

Strong / Tanky bruiser

High Reward Champion if played well

Can carry easily

Can turn your loss into WIN

High Burst (Destroys squishies in spark of second)

Great lane sustain

Cons:

Item Dependable

Not that good against range Solo TOPS

Viable at Mid - Late game (Depends on farm)

Farm dependable

Irelia is very tough anticarry / antisquishy champion which deals DMG like assassin (Which she is), dies like tank and heals herself like support. With combination of good items, she is high rewarded and high viable in mid - late game. She can often turn lost game into win.

Going 0/9/21 is IMO best opinion playing Irelia.

21 Utility mastery points provides you everything u need such as Mana regen for your abillities, Health regen for sustain in lane phase, Movement Speed which u want since u play Irelia ,,high mobility,, champion :).

9 Defensive mastery points for quite higher defensive stats.

Marks= Armor penetration are most viable marks for Irelia.

Seals= Flat Armor / Dodge seals, both options viable. Depends on your playstyle.

Glyphs= MR per LVL glyphs are best choice for Irelia.

Quintessences= There are 3 Possibilities.

1st : Armor Penetration = Provides u nice dmg by ignoring Armor. Good Quints for agressive players.

2nd : Health Regen = Really powerfull option if u want to sustain in lane for long time and if u prefer playing deffensively.

3rd : Movement Speed = Provides really nice mobility and in mid - late game, it's almost impossible to escape Irelia with FON, Mercurys, TRIFORCE and theese. Master Yi should be scared !!! :))

As always, there are many possibilities.

FLASH

Usefull for every Champion. U want that to escape ganks, escape from tower diving, fake moving. Also possible to use it offensively. Just however u want.

GHOST

I prefer using Flash, but Ghost is also viable. It speaks for itself. Can be used defensively, or offensively.


(EVERY CLASS SHOULD HAVE ESCAPE MECHANISM)

TELEPORT

Very often used by solo top players to get to lane quickly, to get to Dragon fight when it's forced, or just backdooring.

IGNITE

If u feel like u gonna grab some kills on solo top, or just wanna be more offensive and harass.

Startin Items:
+ or

Both options help sustain in lane. Both Regen and HP will help you through the game until u sell them for better items.


Early Game:

Every game is situational. So if u feel u need more magic resistance go for If their team is heavy AD, go for . Anyway, u need boots.
Another goal early is starting to build TRIFORCE parts. If u feel u need bigger survivability and u are target of many ganks, HP which provides help u a lot and with your E skill, u are hard to kill.
Otherwise, if u dominate the lane and being not harassed go for because it provides nice burst with combination of your Q and W and u can secure some kills on not carefull enemies.

Mid Game:

and are absolute must. BOTH CORE ITEMS. U want it ASAP.

Late Game:

IMO best late game items are:
(Attack speed scales well with your W and MR is always valuable + passive *DMG*)
(Against heavy AD)
(Against heavy AP) .
This Build completely fits current META which is Bruiser + AP + AD. Sometimes Double bruiser or Double AP. It is balanced and IMO really good build.
Sequence of items depends on situation in game, but for me, this is really well balanced Item Build for Irelia Late game. Dont Forget to sell your Starting Items.

Other Viable Options:
+ If u wanna go little bit beefy with nice dmg.
Against annoying CCs, but IMO i dont buy this, cuz Irelia's passive is really OP, so u dont need it that much + u are not target of enemies' CCS that much in team fights.
Against Heavy AP. Currently good against double AP META.

Passive: Ionian Fervor

Each nearby enemy champion (to a maximum of three) reduces the effectiveness of Crowd Control on Irelia.1 Champion: 10%2 Champions: 25%3 Champions: 40%

Explanation:


IMO really good, if not one of best passives in game. Its almost impossible to get killed by CC ganking champions. Irelia is almost unlockable in Team Fight, nothing can stop you to take squishies down.


Q: Bladesurge

Irelia dashes forward to strike her target for 20/50/80/110/140 (+1 per Attack Damage). If it kills the target, Bladesurge's cooldown refreshes and refunds 35 Mana.

Cooldown 14 / 12 / 10 / 8 / 6 seconds

Cost 60/65/70/75/80 mana

Range 650


Explanation:


Even if u want farm much faster, always try to autoattack first. If u are denied, u can use your Q. This is really nice tool when u are harassed. Even harassed, u can kill all the creeps under tower. Also deals really nice dmg to squishies.

Tip : By using your Q, your Sheen Activates and thanks to recent patch, u automatically autoattack after successful landing it = Nice BURST which is insane in combination with your W. (W for true dmg on autoattacks + Q dmg + Sheen proc + autoattack = Insane burst, especially for squishies. Dont use this that much, because it's really Mana hunger combo early - mid game)

Tip n.2 : Remember that your CD on Q resets after killing minion. This can be used for Chasing, or Escaping.


W: Hiten Style

Irelia is skilled in the art of Hiten, passively giving her physical attacks 10 / 14 / 18 / 22 / 26 health restoration. Activating Hiten Style adds 15 / 30 / 45 / 60 / 75 true damage to her physical attacks for 6 seconds.

Cooldown 15seconds
Cost 40mana

Explanation:

Irelia's daily Butter and Bread. This is thing which essentially makes Irelia. Passively, it gives lifesteal per hit. By activating, gives u nice amount of true DMG ! Also makes Irelia very hard to be harassed. Her sustain is really good thanks to this passive.

Tip : By activating W, passive doesn't disappear so u also heal yourself and deal True Dmg.

Tip n.2 : Well synergizes with Attack Speed (TriForce, Wits End, ....)

Tip n.3 : Your passive ability also heals herself when dmging Towers, etc.


E: Equilibrium Strike

Irelia's attack balances the scales, dealing 80 / 130 / 180 / 230 / 280 (+50% of ability power) damage and slowing the target by 60% for 1 / 1.25 / 1.5 / 1.75 / 2 seconds. However, if the target has a higher Health % than Irelia, then the blow stuns the target instead.

Cooldown 8 seconds

Cost 50 / 55 / 60 / 65 / 70 mana

Range 425


Explanation:


Really strong Ability. This makes Irelia real nightmare in dueling and ganking. Decide wisely if to use it to slow or stun. This is real NEMESIS for enemies as long as Irelia sustains in fights.

Tip : Well used E can make u survive Ganks or Duels or Score Kills. When tower dived, your E can save your life and also get u a KILL, especially in combination with IGNITE.


R: Transcendent Blades

Irelia summons 4 spirit blades that she can fling to deal 80/120/160 (+60 of attack damage) (+50% of ability power) physical damage to enemies they pass through. She heals for 25% of that damage against champions and 10% against minions.

Cooldown 60 / 50 / 40 seconds

Cost 100 mana



Explanation:


Really usefull ultimate in all aspects.

U can spam it thx to short CD.

Tool for Clearing minion waves. (Remember, Ulti scales from AP and u need at least Sheen to clear one minion wave by 1 ulti)

Good tool for sustain thanks to healing.

Nice tool for finishing when chasing, or just nuking someone in team fights.

Provides nice dmg and healing in team fights.

Starting with Q or W. Just whatever fits u. Anyway U don't find yourself to be harassed that much on LVL 1. At all, it doesn't depend on first skill, skill maxing sequence is most important.

U want to max your W first thanks to it's true dmg and healing. U will find yourself laning against tanky champions so true dmg will avoid them to leave without scratches and in hard times, u will just heal yourself by not just last hitting.

U Want to max your Q second thx for not being denied on minions, thx to dmg it deals, thx to combinations with your other 2 skills which deal real burst.

U want to max your E third because in lane phase and farm phase, only it's stun and slow is needed. Dmg is not needed that much and u still have your true DMG.

U want to max your R (Ulti) ASAP.

Early game is essence of farming. Irelia is really item dependable so u become really scary with about 3-5 items. Just play carefully until 5-6 LVL, when Irelia starts to shine most. Try to be more agressive and when u figure out that u can't handle THAT enemy, just stay passive and last hit minions near tower with help of your Q. After u get your Sheen, try to be little bit more agressive again and slowly dominate your lane. Stay Farming whole EARLY game.

Mid game is also in essence of farming and getting gold to make Irelia moving behemoth. I don't recommend u to leave your lane, or stop farming to get to fights until u at least have Triforce and Guardians Angel.
(Except forced fights for DRAGON).

When u obtain these 2 MAIN GOALS, u should join your team to fights and go straight to late game + become nightmare of enemy carries and squishies.

Now u are moving behemoth. Real nightmare for enemy team. High defensive, scary offensive insane something, that can turn fight/game into your benefit. U should have something about 450-500 Movement speed, so almost nobody can escape you. Since u are tough, beefy and high defensive, u should initiate fights for your team, and naturally lead. U are the one who destroys squishies in 2- 3 slashes so u should not worry about your team being killed by enemy carries.

As already has been said, u are now really tanky and real nuke for squishies, u should engage for your team for eternity and force enemy carries to get out of fight, in best way (which is 95% probable) kill them.

Choose wisely, which team fight is good for your team. Depends on terrain, narrow paths, brushes etc.

That is Irelia. Real Nemesis of enemy. THE One with DMG of assassin, and defense of bruiser. Put Irelia at edge of her limits and u will be satisfied like never. Hope u liked it. However it is my first guide.

I wish u good luck playing Irelia and other Champions and all for all, DO have a fun playing League of Legends. There are enough ragers in gaming World :)

EDIT : Copied by myself from Solomid.net

CYA