Hello fellow summoners this is unfazed and I have made another fantastic guide just for you. We'll be building Irelia, since we love hiten style! Ok let's get started!

For spells I use Flash and Teleport for more map control. You can use Ignite instead of teleport if you want to secure kills, or Barrier against high DPS.

Irelia's passive is Ionian Fervor which decreases the duration of cc on her based on how many enemy champions are nearby. It adds up to tenacity,given by certain items, like Mercury's Treads for a total of 75% reduced cc when 3 or more enemies are nearby.
Her q is Bladesurge which jumps onto an enemy unit, dealing physical damage. If it kills the target, it's cooldown is refreshed and some mana is restored, but not all of it, so be careful not to overuse it. Max it last.
Next is her w Hiten Style, which passively heals you for every basic attack, whether you attack a minion, a champion or even a turret, pretty much everything. When you activate it, the healing effect is doubled, while your basic attacks deal true damage for 6 seconds. You need enough attack speed to make the most out of this ability. Max hiten style right away.
Her e is Equilibrium Strike, which deals magic damage to a single target. If your hp percentage is higher than your enemy's, they will be slowed, but if it is lower than theirs, they will be stunned. EXAMPLE: If you have full health, at 2000 hp and your enemy has half health at 2100 hp, the enemy will be slowed. Yes, his current hp is higher than yours, but with percentage he has 50% (half hp) and you have 100% (full hp), so you have higher percentage than him. Max e second for more cc duration.
Irelia's ultimate is Transcendent Blades which fires projectiles towards your cursor's location, dealing physical damage and healing Irelia if they hit. You can activate this ability 4 times before it goes on cooldown.

PROS
+ natural sustain, thanks to Hiten Style's passive
+ Gains true damage on basic attacks when activating it
+ Can farm easily using her Bladesurge
+ mobile, can use q to juke enemies
CONS
- relies on mana, which she often runs out of
- can be denied farm easily, cause she is melee and gets poked
- Using Equilibrium Strike can be tricky, might not work as planned, due to miscalculation of you and your opponent's hp percentage

Start with a Doran's Blade and a Health Potion. Doran's blade offers good early stats, while also combines with your w, for extra healing on attacks. When you get back, grab another doran's blade, and Mercury's Treads for tenacity, which works well with your passive. Start the Phage in order to build your big item later. Finish your Trinity Force right away, then pick either Blade of the Ruined King or Wit's End, based on what you need most. Botrk can destroy tanks, while wit's end is better for squishier targets, and gives some mr too. Gor for a Frozen Mallet for infinite slow and massive hp, follow up with Randuin's Omen and finish your build with either Guardian Angel, Spirit Visage or Banshee's Veil. You will be tanky enough to take damage and still be able to kill a target. When you finish your build, you can replace your boots with Zephyr.

That's my guide for Irelia guys, hope you enjoyed, please leave a comment if you have any questions or suggestions, I'll be glad to hear any of that!