This is my first attempt at a guide, so please be gentle. And I have no idea how applicable any of this is to ranked games. Perhaps not at all.

For me, what makes Irelia stand out is her situational flexibility. We've all solo-que'd, been placed with non-communicative players that pick champs like Maokai, Blitzcrank, or Alistar, making us dutifully pick squishy nukers and DPS champs. Then they build AP, and you're left tankless. Irelia is one of the few crossover champions that can, with the right build, successfully offtank and initiate in that less-than-ideal situation.

Or, she can go straight nuke, taking a Trinity Force, Hextech Gunblade, Brutalizer, and maybe a Bloodthirster and/or Black Cleaver and rival your standard mage or AD carry in terms of sheer damage output.

Which is why I love (and hate) Irelia. Because she can fill in multiple niches very well (and is very frustrating to try and explain how I build her.)

Runes are a matter of personal preference, but I go for tankiness and armor penetration.


Greater Quintessence of Desolation Greater Quintessence of Desolation
Greater Mark of Desolation Greater Mark of Desolation
Greater Seal of Resilience
Greater Glyph of Warding

Occasionally, I'll switch it up and throw in some health or dodge runes, so those are worth considering too.

I feel the same way for masteries--mostly personal preference but I prefer to slant tanky, so the 21 there is obvious. Aside from that, I like to put my 9 in offense so I can get the AP boost from Ignite's CD (not huge, but AP does scale with your E and R and you're probably using Ignite anyway). However, 9 on utility isn't bad. Good Hands and Perseverance are good choices, but I find I don't like any of the third level utility masteries.

Best:
Flash: Standard after level 12. Amazing escape mechanism, can jump over walls, and occasionally useful in chasing down that champion at 15 HP while your Q is on CD.

Ignite: How many times do you find yourself out of mana with all your skills on CD, while that same 15 HP champ is fleeing from you? And don't lie, because you know it's happened to you. Also useful since it is ranged, and Irelia is melee. And always useful against stealth champs and Trynd's undying rage since the damage-dealing persists.

Also Good:
Ghost: Not as good for fleeing as Flash, but better for chasing.

Teleport: With a jungler on your team, Irelia is a great solo top choice. In those situations, I love Teleport as a way to quickly get down to bottom lane for some 3v2 action. But other than that, I'm not a huge fan.

Exhaust: Nothing against it, just not my style. Other people swear by it, and it certainly isn't a bad decision.

Serviceable:
Heal: I secretly love it early game, and it's useful in a teamfight, but it just it just doesn't heal enough after the first 10 or so minutes.

Passive: Ionian Fervor - This, plus Mercury Treads will make you the enemy of Lux's everywhere.

Q: Bladesurge - This is the best last-hitting skill in the game, and makes Irelia an incredible melee farmer. Don't auto-attack (which you really shouldn't be doing otherwise), and simply Q minions once they get to the end of their life. Later in the game, an easy rhythm develops--two auto-hits and one Q to kill a minion. Rack up the farming. Just make sure you leave your lane partner some minions of his own. It, followed by a quick E, are also great for chasing down fleeing champs and alright to initiate when needed--of course, always let the tank initiate first if he's even marginally competent. The Q/E combo, often with a W thrown in, is your bread and butter int terms of harassing, attacking, and killing enemy champions.

W: Hiten Style Early game, Hiten's passive is a lifesaver, and makes you very sustainable in lane despite being melee and not (yet) tanky. When low on life early game, auto-attacking a few minions can be the difference between going back and staying in lane.

E: Equilibrium Strike Something about this skill is poetry. And let's just be blunt; the majority of awesomeness you will preform in a match will come from your Q/E combo. Jumping in as your squishy is being ganked to stun one of the gankers so you can both escape will make you a hero of the team. But, more importantly... jump halfway across the screen to their squishy champion, their half-dead champion, or their fleeing champion, and instantly stun/slow them while dealing them an incredible amount of damage. Once Annie realizes the teamfight is going badly and she needs to run to the nearest turret, she's probably already only one Q/E combo away from death. Except, even if she survives....

R: Transcendent Blades - ...pull out your blades. Four blades, all skill shots, which do damage while healing you. And casting them doesn't interfere with your movement, so you can shoot them behind you while running away or in front of you while they run away. Or toss them into a minion wave to kill them and heal roughly half your life. It doesn't deal the most damage, but hurling these while you're alone under a turret will often make even 3 would-be-pushing champs instinctively turn back.

As for order, I always start Q, W, then E. Q is necessary to get first to begin properly farming, followed by W to help you stay in lane. But I max them in the reverse order because of scaling--E scales best, while Q scales worst.

So, this is the bread and butter of the guide, because as I said in the introduction, she is so versatile with how you can build her. So, let's begin:

On Those Two Items Every Other Irelia Gets:

Heart of Gold and Philosopher's Stone Philosopher's Stone.

No, I do not get these items. Yes, I know everyone recommends them. Here is my line of thought.

1. Additional Gold: Most Irelia builds are extremely expensive, and need the extra gold flow, but this isn't a particularly expensive build. Trinity Force is expensive, as is the Hextech Gunblade that you may not even get, but that's about it. Frozen Heart is moderately priced and everything else is flat out cheap. So, with a build such as mine that emphasizes rushing out cheaper items in the early game, you don't need the additional gold. Especially if you are properly last-hitting minions with your Q.

2. Lane Survivability: This Irelia build already makes you very survivable in lane. Beginning with two health potions, and quickly building defensive boots and probably 1 or 2 very cheap defensive items, the additional health and health regeneration isn't necessary to stay in lane. (And the mana regeneration, after level 3 or 4, is simply useless.) Especially since Irelia already has a passive W and R that can regenerate health. If you're in lane, and you're low in health, auto-attack or fling your R into a wave of minions for a moment.

I understand that most Irelia builds are improved with these two items, but this is an Irelia build considerably cheaper and tankier than your standard Irelia, so I simply don't think they're great items for their build. Obviously, extra gold per second, health, health regeneration, and mana regeneration (all of which, in very small amounts), make pretty much any champion better. But are either of those items one of the 6 best items to put on this Irelia? I say no.

The only exception I can think of is against an AD-heavy team, where you want to commit to a Randuin's Omen. In that case, go ahead and get a Heart of Gold early.

Opening Items:

I start with basic Boots of Speed, one mana potion to fuel my constant Q'ing as I farm in the first few minutes, and 2 health potions to keep me in lane as long as possible. The first (or second) time you go back, you need to make a decision. If you're doing well, go straight for the Trinity Force. If not, go for the value defensive items first, depending on who's harassing you. Often, I go ahead and get both. Then go for Trinity Force after.

Core Items:
Mercury's Treads
You pretty much always need extra magic resistance, right? And the CC reduction combined with your passive work very well. Although, very infrequently, I recommend Ninja Tabi if for some reason, their team is almost all AD and lack crowd control.

Trinity Force
So many cool things, and they all work perfectly for Irelia. The end. I usually go Phage, Sheen, then Zeal, but most people seem to prefer Sheen first. I just love getting the added slow effect of Phage as soon as possible. That, combined with your boots and natural speed, should make you able to chase down most any champion fairly early on.

Value Defensive Items:
I usually run one or two 'value' defensive items, depending on the enemy team's composition. One magic resistance and one armor. They're cheap enough to not dominate your build, but I find that their worth in keeping you alive far exceeds their cost.

Spirit Visage
Cheap magic resistance paired with cooldown reduction. And Cooldown reduction is great on Irelia. The more times you can get off your Q/E combo, the more kills you'll rack up.

Warden's Mail
A cheap source of armor and health regeneration. Paired up your W's passive, you have amazing early- and mid-game lane sustainability. And the slow affect is useful in fights. Since Irelia isn't the most common champion, people often don't respect either her damage output or tankiness. Or both. So if they start a 1v1 fight with you, and quickly realize they're outclassed, you'll be more able to turn around finish the kill.

Wriggle's Lantern
When faced with a jungler or stealth character (Evelynn comes to mind), I opt for Wriggle's Lantern instead of Warden's Mail. Same cheap source of armor, lifesteal substitutes for the health regeneration in terms of sustainability, and the bonus of a ward helps protect you from ganks and keep up the fight against a cloaked Evelynn.

The Next Step:
So, you have your Trinity Force, and you may or may not have one or two of the cheap defensive items as well. Ask yourself what do you need? If you're now finding out that you need extra defense you didn't earlier, look back up at those cheap defensive items. If you already bought them and need more, go ahead and firmly commit to the offtank route. Or, if you are owning the map, killing everyone you can find and escaping untouched, then keep the offense rolling.

The Brutalizer
The last of the value items... and, admittedly, not the best value actually. But the attack damage and cooldown reduction works really well on Irelia. And you can always sell it back later, or build it into a Youmuu's Ghostblade but I usually don't, if for no other reason that the game is usually over before I decide I should make the upgrade.

Hextech Gunblade
Yes, it is expensive, but I think it's worth it, especially if your build thus far has been fairly cheap. One thing I hate about Irelia is her mix of AD and AP, and this is one of the very few items that adds both to improve damage output from all of your skills. And it matches that with both lifesteal and spellvamp. And, it gives you, as a melee champion, the addition of a ranged attack. AD, AP, lifesteal, spellvamp, and an additional ranged attack that also slows. Sign me up.

Frozen Heart
Again with the cooldown reduction. CDR is vital to Irelia. The more times you can get your Q/E combo off in a fight, the more kills you'll get. The armor bonus is insane, especially if you're going up against an AD-heavy team, and the extra mana is... nice. Not great, because you shouldn't have any mana shortages after the first few levels, but useful.

Force of Nature
Similar rational as Frozen Heart. The magic resistance bonus is huge. And, with a judicious play style, the added health regeneration combined with your passive W (and perhaps a Warden's Mail) will make you an unmovable force in mid game in lane, or holding turrets late in game. Going back? What is this 'back' of which you speak?

So, there you have it.

Irelia's strength is her versatility and dual nature. With only one (or no) other tank on your team, you can dutifully pull off a very successful offtank and relieve a lot of pressure from your team. In a more well-rounded team, with a more offensive build, you can still take your fair share of hits when the tank inevitably falls, while packing a serious and sustained punch of auto-attacks and your Q/E combo. So I think I've presented an appropriate build with a few options that will let you take a lot of damage while dealing a lot of damage. Because that's just what Irelia is all about.

I tried to keep the guide fairly brief and succinct, because I personally hate guides that fall into million IF this, THEN that motifs for paragraphs upon paragraphs. If you think I made any gratuitous errors, let me know because you're probably right. And, since Irelia is actually my main, if you think you have better ideas, let me know.