I've been trying to rush Blade of the Ruined King on her more often now to have a reliable slow that isn't red buff, and for extra anti-kite power. Looks to me like you're going more tank, which works just as well, but I think around ~170 of each resist is good enough. Personally I've been getting Hydra on her for tons of initial damage when you dive into the enemy team and Q all of them. The lifesteal helps too but I'm not sure if it's overkill or not. I'll try something like this next time I play her maybe.
Of course, last time I played her it was kind of a stomp and I built full damage, so, there's that. I find Zephyr nice on her as a later item if you don't get the Mercury's Treads. The incoming changes to Wit's End are going to be very nice for someone like her though- you should try that out when it happens.
As for runes, since she does a lot of magic damage on top of her auto attacks with her E passive and W altogether, I've actually been working on hybrid penetration runes (that is, marks and quints) to the point that I still have 10 armor penetration, which is enough for the jungle, and then some magic penetration as well. I think a guide I saw had 6 hybrid penetration and 3 attack speed marks? I don't remember.
EDIT2: Got on to screenshot it, it's looking like this-
EDIT: Why offensive masteries if you're building mostly tanky?
writing builds for an unreleased champion you've played twice in customs np np
I'd do my own but the only champions I feel confident enough for that are Quinn and Fiora and well they're not exactly popular- I'd more or less just be re-writing the guides I took small tips from and/or stating the obvious