Irelia was my champion of choice for escaping elo hell and grinding the ladder. Currently, my elo is at 1780 with 17 wins and 0 losses on Irelia. Her strength lies in her ability to beat bad opponents. In elo hell, you need to be able to do one of two things: tank an entire team or kill an entire team. Irelia can do both. Her dominating lane presence and ridiculous steroid in Hiten Style make her one of the strongest tanky DPS characters in the game.

The only core runes for Irelia are the armor penetration Marks and Quints. Her ultimate deals physical damage, and armor penetration helps with the damage accordingly. Seals/Glyphs should be by choice or help set you up in whatever lane you are facing (armor/magic resist). I find myself usually wanting some extra mp/5, however that part of the setup is choice.

I usually use a 0/9/21 setup. The offensive masteries offer Irelia very little and should be avoided, however her biggest gains are from the utility tree. This tree gives you lots of cooldown reduction plus the awesome benefits of movespeed and shortened cooldowns on summoner spells.

Flash and teleport are the two best skills Irelia could have. Flash gets you out of those sticky situations that Irelia puts herself in (such as top lane, bladesurging in, or towerdiving). Teleport allows for the hardest lanes to be won and adds a global presence to the team harassment.

Starting Items
Irelia has several strong starting items, Doran's Shield, Doran's Blade, Null Magic Mantle and 2 pots, or Boots and 3 health pots. Each item should be used depending on situation and fill a different role.

Doran's Shield: Very strong against laners who have a lot of early physical presence, such as: Urgot, Tryndamere, Renekton, and others.

Doran's Sword: I use this item usually when I lane vs. other tanks such as: Cho'gath, Warwick, Udyr, Malphite, and Jarvan IV. Doran's Blade is very unconventional, yet effective. It gives you increased damage and lifesteal, both which come into effect in a melee vs. melee lane.

Null Magic Mantle: Strong AP Carries that do not rely on skillshots. These champions give Irelia the hardest time out of any champions in the game and must be countered, accordingly. Annie, LeBlanc, Vladimir, and Malzahar are a few examples.

Boots: Boots are great for laning against champions with either a lot of early harassment or has damage based on skillshots.

Lane Match-Ups
Irelia thrives in the ability to beat even the toughest tanks in lane. In my opinion Irelia is the strongest melee vs melee hero in the game (the only rough matchups being Warwick and Tryndamere).

Powerful laners such as Udyr, Warwick, Cho'gath, and even Jarvan IV can lose to a good Irelia player. Her strength lies in her kit's synergy with Sheen. Irelia's ultimate proc's Sheen anywhere from 2-4 times while it is active and her Bladesurge applies it. Combine this with her true damage, her stun, and her innate lifesteal to get one hell of a laner.

The AP carries are sometimes very rough for Irelia. Any champion with lots of burst damage/range can shut her down very easily. However she usually can still farm under her own turret.
Examples of difficult AP lanes are: Annie, Brand, Cassiopeia, Rumble and Orianna.
Stalemate lanes should be played passively and your entire focus should be on farming. These match-ups are: Malzahar, Gragas, and Kennen.

The other AP lanes are very winnable and should be played rather aggressively (generally starting aggression around level 4).

Farming
Irelia is very farm dependent. Try to stay in lane until you have at least 150 CS. Feel free to use teleport aggressively if the situation occurs, but try to focus on farming. The sooner you have a complete Triforce the better.

Irelia has a relatively weak teamfight early game, however if a fight occurs, try to avoid the burst damage and cleanup.

Early Items
A lot of Irelia players like to build Gold per 10 items i.e., Heart of Gold and Philosopher Stone. These item's aren't bad, but they decrease the early game damage Irelia has with Sheen. In my experience, they should only be built if you know for a fact that the lane will be a stalemate. Often you will find that building a Sheen first is the difference in winning or losing your lane.

After Sheen you should complete Mercury Treads and Trinity Force in an order that you see fit. Once your Triforce is complete, try to move away from the laning phase, as your damage will be quite high at this point. Try to only fight when your ultimate is up. Engaging on the enemy champion near a minion wave and using your ultimate can setup a blowout. The heal + Sheen procs from Trancendent Blades is very good.

A few other tips:

1) When using Bladesurge to attack a champion, be sure to activate Hiten Style first, as it will apply the true damage.

2) If possible, lead with stun and save your Bladesurge. This means you will lead with a stun and be able to finish with a gapcloser. It increases the total dps by resetting your attack animation and applying that last sheen proc. Anytime you can do this freely, take advantage of it.

3) Minion hopping, when you kill an enemy with Bladesurge, it resets the cooldown. This means that if a caster minion is low, and the enemy champion is behind them, you can dash to the caster minion, kill it, and then follow up on the champion. This is called minion hopping. Using a low hp minion to close the gap on the opponent, it's something that you should be aware of and take advantage of when possible.

4) Farm under the turret using Bladesurge. On caster minions, let the tower hit them, auto attack them once, then immediately Bladesurge them. This should be enough to kill them everytime. Melee minions generally take 2 tower hits and then 1-2 autoattacks to die, use bladesurge accordingly and you should be able to get every minion under the tower. If a minion is taking fire from your creeps, try and burst them down.

5) Try not to use Trancendent Blades to clear minion waves unless you are intentionally pushing the lane, or under extreme pressure. This will keep the lane at your tower, right where you want it.

As explained in the previous section, the starting items I use are, Doran's Shield, Doran's Sword, Null Magic Mantle, and Boots. For an explanation, please look at the Laning phase section.

The first item you should look to complete is sheen. Often times the difference between winning your lane and losing your lane is the extra damage that sheen gives you.

Often people build philosopher stone, which is not terrible, however it puts you behind on your build and lowers your total damage output. Only buy Philosopher Stone if you are in a stalemate lane. Rushing sheen gives you the extra burst you need to finish off small skirmishes in lane, and to pull through for your jungler when he ganks. The benefit from the Sheen proc is at it's best with Irelia. Q applies it, and her Ultimate can activate it up to 5 times. This is also one of the reasons she is such a good triforce, and again, I believe winning your lane and rushing this item is much more important than fiddling around with Gold/10 items.

After completing sheen I usually finish up merc treads and begin to build either Zeal or Phage (depending on the lane). Farm until you can finish Triforce.

Typically
After Triforce you should look to the other team to see what is best as the next item. Aegis of the Legion is usually what I build and a very good baseline. However if someone else on your team already built the item, look for something else that will give you the HP to keep you moving forward, or look at the items listed below.

If you are Ahead
Build a Wit's End. The attack speed and magic resist work very well with Irelia's kit, and will help keep you ahead.

Against Strong Initiation
Banshee's Veil will keep you and your team from being caught in bad positions. It also gives you the extra hp to reach the 2600ish mark, which is about where you want to be.

Look to Balance Your Mitigation
After your 3rd item, look for something that will round you out. If you aren't at the 2500+ hp range, look for a purchase such as Sunfire Cape, Banshee's, or even just a Giants belt. Reaching this mark allows you to build the straight mitigation items that really push your end game.

Guardian Angel is probably the best end game item you could purchase. It allows you to tank their team, revive, and continue fighting. It works especially well with healers, so look to your team and explain to them what you plan on doing.

If the game goes on longer, Last Whipser, Atma's Impaler, and Frozen Heart all make excellent choices to fill out your inventory. In some cases, even look to purchase a Madred's Bloodrazor. The item allows you to eat up baron, enemy champions, and super minions (hopefull it won't come to that ^_^).

Hope that helps, if you need any more explanation please post in the comments!

Mid-game should be spent roaming with your team and farming lanes that are pushed. Red buff is especially strong on Irelia mid-game; ask your jungler to give it to you for most of this phase. At lower elos you should try and pick off the other team. Often they will not be grouped, and Irelia is an incredibly strong 1v1 fighter. Place wards in their junglers and take advantage of lanes that need farm. Catching a carry mid-game can earn you easy towers, dragons, and sometimes barons.

Continue your farm and begin to expand your item build. Sometimes building damage items such as Wit's End and The Black Cleaver are necessary, but again, do so only if necessary. Otherwise begin to build tank items. I really like building Aegis of the Legion, it gives you a lot of strong stats and is a valuable asset to the team. If no one else is building it and the opposition has a relatively balanced team composition, it is a good time to buy the item.

In team fights feel free to dive the carry, but if you are bursted hard, try and dash out. Initiating without bladesurge usually results in a stun from equilibrium strike. Again, this is a very powerful thing you can do, but it involves catching the other team out of position.

At this point you should have finished a couple of tank items and should begin building towards Guardian Angel. Nothing is more terrifying than an Irelia that comes back for seconds. In team fights you should focus on trying to soak most of the CC with your passive. It is okay if you take a lot of damage, as Irelia is very good at escaping. You still should be focusing the carry, but it will be harder to do so. Timing is everything, if you can catch their team with one mistake, or find their carry alone. You can change the teamfight by yourself.

Do not be afraid to make an early exit. Often people will chase Irelia, but she has a very high base movespeed and is naturally resistant to CC. Doing so can help turn the teamfight into a 5v3 or 4v2. Once you have escaped, look for an opportunity to dash back in, Irelia still has an amazing cleanup.

There isn't one specific build I would encourage seeing how all games are very situational. This guide is to help you get a sense of how to play her in your ranked game, but everyone's playstyle is different. I started playing her around 1100 elo and raised up to the 1700's playing her every once in awhile along the way. I hope this helps and goodluck!

-Nyvia