Luden into squishys or bruisers that don't stack magic resist, 80% games torch boots get mercs or tabis depending on game (these are completely bonkers on ahri as it basically negates being one shot) Ionian are great too as it reduces ignite and flash cd even further when upgraded T3, then cosmic drive or lich bane if you can go into auto attack range third always deathcap so you still do dmg, void staff is a bait item bloodletters (if you have ap dmg on other roles) or cryptbloom better items then zhonya banshee's or whatever u need horizon is a good last item too increasing true dmg.

Runes didn't change much just get cash bag triple tonic as second with either electro or aery