So bros, irelia top lane. What to do and why?
I have been playing her a bit and it is cool because you can carry from top lane, and she is very hard for the enemy to counterpick. What I have done so far is that I go boots pots early, then I get philo stone for superior mana regen and if I still hang on turtle heart. Then around lvl 13-15 I get wits end, and then next triforce. At this point the game is won.
Am I going too much gold items?
There are many ways to play Irelia (which I think is a good thing), but this also leaves many less than optimal routes open. She's generally hard to counterpick because she can get away with most items. I generally do not like to go gp10, as this makes her weak early, and makes her dominate lane less. I'd only really consider it if I got a really early kill, (and still then, I'd usually consider items that'd let me bully my lane out). Against heavy AD harss (GP, Riven, other irelias etc.) you'll want to go cloth armor (or boots, for easier harass/escape) into either wriggles or tabi (or both if you're really f'ed). Many people consider Irelia's weakness to be her early game, but I disagree. From lvl 5 and forward, her W makes you able to trade with almost anyone. Trinity force is VERY situational, and should be left out more often than not. It's very pricy, and farming it weakens your lane (less defensive items). You'll usually want to buy it, only if you're laning someone you can't kill without burst (Vlad or panth for example), or if your team lacks damage.
Depending on match-up I'll usually hover around the following builds:
Heavy AD: Cloth armor into tabi or wriggles (wriggles is a huge money sink if you don't need it badly) > phage > frozenmallet / atmas (if lane is still hard). At this point I'll usually transition into Wits End for MR and easier trades. If I make it to lategame and I still haven't upgrades to frozen mallet, and I'm not being focused hard I buy Trinity force, but more than not I end up going frozen mallet (that slow is so great).
Heavy magic damage: boots into mercs > wits end > (chalice or early negatron if im raelly getting it, or laning rumble, fk that guy) > phage, into normal build.
Everything else: A mix depending on their team, and how my team is doing.
Exceptions: If you get an early kill or two, and get a phage or wits end, going zerg greaves will ensure the rape that is to commence. Can always swap them when teamifghts come along.
When laning against someone you really need to burst, an early sheen will help loads.
A typical full build will usually (again, everything is subject to change, depending on who's fed and who's not) consist of some of the following: Merc threads, Frozen mallet, Atmas, Wits end, Guardian angel / force of nature / randuins or madreds if you feel like you're already winning and want great lulz.
What I've learned from playing lots of Irelia, is that there's almost never 1 item that you must have. Everything changes, and you learn to adapt by playing a whole lot of her.
A note on early philostone: Shurelyas kicks ass on her.
EDIT: Triforce Irelia gets raped by Fratmas Irelia.
e(Karma)+Undead_Phoenix(Galio)
