Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is just some fun build ive been toying around with, sheen plus hextech is a great combo and makes ur equilibrium strike deal heavy damage. Not to mention the amount of slows and stuns u can cause in combination with gunblade makes her a great ap ninja. In addition, having boots of swiftness is great for ganking along with ghost and flash for a ninja getaway or to get in range of her abilities. Only problem with ap irelia is it makes her like a mage i.e. very squishy glass canon who relies on abilities to hit the damage. However the burst ap damage and 'ninja style' is very enjoyable to play with irelia (its like all those ppl who wanted kas to be melee, which is just wrong, so they can now use irelia like this!). Basically you ghost towards your gank, then bladesurge at them, then equilibrium (and repeat with atks) or if in trouble then flash away.
A FAST STRIKE IN AND OUT! NINJAAAAAAA!
GL HF :)