Irelia is one of my favorite champs in the game other then morgana. throughout my time playing her i've developed an almost sense on how to make her awesome. first thing you got to know is her core you dont have to try my build exactly but the core of Irelia and arguably any good assassin is Mercury Treads and Trinity Force. with her passive Irelia has 75% tenacity in a team fight which makes her one of the best champs to engage with. One other thing i have to mention is use her ult accordingly she really lacks in farming other then her ult or a well timed q spam but even then that q could take a while.

Runes aren't that temperamental with her so its really a choice of your own. when i usually play her i aim for a decent offtank with a high damage output which this build supplies. I use the dodge chance because dodging is better then getting hit and in my build you naturally build armour so armour runes are almost pointless if you want loads of armour then play rammus he has no problem with that ;)

With my mastery page i'm again aiming for that offtank. since i play assassins I know how squishy and focused they get so irelia is one of the better assassins to start out with as long as you dont get too cocky. since assassins have a high damage output i only keep the 9 in offense cause i know she can kill as long as she can live and thats where the 21 in defense is added into perspective