Hello and first of all thank you for help and time.
Ok, so Ahri, i have her and played her since her release, but i started playing ranked not long ago, around July or so, right now im at 1080 elo, but i can't seem to carry with her, i have AP runes for my mids that would be Magic pen Reds, Flat AP Yellows, MR blues and flat AP quints with either 21/9/0 or 21/0/9 (depending who i might go against, harass and what not), i would usually go for a tanky build, something like a Katarina build, Sorc Boots/Ionian, Chalice, Revolver, Deathcap, Scepter and never get to build the fifth, i don't make it on that specific order, but each and every game i do with here i end up being more an off support than anything else.
So if you could give me Runes+Masteries and everything you can please, i do love her and i want to play right with her in competitive play.
Once again thank you for your time and help.