I've started playing Irelia recently so I might not be the best source of information for her but I've found this to work and I've mixed a few of the top used builds to make this. The main difference is the skill order. Which I'll get into on the chapter, I hope you enjoy.

+ Best Off-Tank in my opinion
+ If they manage to get you low health Equilibrium Strike with stun them
+ Passive Life Steal and True Damage
+ Attack Speed with the True Damage very good early and late game
+ High damage output on top of tankiness
+ Great Tenacity with her passive and Mercury Treads


- CC isn't great at low ranking
- Not very good at chasing if ghost is down
- Not too much bonus AD so Transcendent Blades don't do too much damage

The masteries are easily changeable, I just prefer utility with slight defense. If you'd like I rotate it to 9/21/0 sometimes, Ardor works very well with it's increased AP and AS, plus tenacity for the reduced damage taken. But in generally I like utility for the movement speed increase and reduced spell and ability cooldowns. Either way they can be used how you feel.

This is where a bunch of people are going to disagree with me but I like it more. I start off with Equilibrium Strike for the CC and if they get the first hit off it is a stun, which is very useful. Then I take one rank in Bladesurge for initiating and chasing which only needs one rank. I than max Hiten Style first for the True Damage and Life Steal. True Damage with the increased attack speed is extremely good early game and late game. Plus the passive Life Steal keeps you extremely sustainable all game. Then I max Equilibrium Strike so you can get the increased CC duration and less cooldown time to use as much as you can in battle. Some people like to max Bladesurge first but with the little AD ratio I don't feel it's that useful for damage output.

Ignite is changeable to your liking but I extremely recommend Ghost. Irelia has a hard time chasing most of the time and it kills me when enemies get away. Though Bladesurge does get you to them the range on Equilibrium Strike doesn't always work with you. Ignite is just there for healers that need to be shut down.