Anivia does really well against
. If you can get the stun off, she's a dead mage. Also, your passive egg can really f-ck Leblancs over, since by the time she actually "kills" you, she'll be waiting on cooldowns and/or maybe be out of mana. Harass her well early, and avoid her chains and try to stay out of range of her W.
Ahri (in my experience) does great against champions with little mobility, as she's really skillshot oriented. However, it depends on skill as well. Usually, you'll do well against
. You have good health sustain in lane (provided you don't run out of mana) while Xerath sustains well in terms of mana.
are kinda lacking in escape, just be careful of Karthus' wall since it lowers your magic resist, and dodge his Q as often as possible. Also, Orianna's shield gives her magic resist, so avoid wasting your spells on her while it's being used and don't trade autos with her. Ahri usually is great at zoning out melee champs. Be careful about when you use charm and Q, because you're very vulnerable without the cc and movement speed.