2 Items that nullify her damage and ability to hurt you:
To remove her Root
Why even bother?
Because this allows her to maintain a subversive power over you while she's waiting on her cooldowns.
A good Le Blanc will bait you to use this and then attack you during it's cooldown.
To Avoid Damage and Bait an Ability
This should be obvious.
In a 1v1, Le Blanc has to use an ability to remove your spell shield, it's unlikely she'll use her Q, R, or E so you have a chance to bait her first ability and make her waste it. At the very least, she will dash to you to remove it then Q-R to deal damage, which means she loses her ability to second cast E and relies on the previous spot being safe enough for her to go back to which then your team can wait at that spot while you dish out your own damage.
A good Le Blanc will dash first to remove the spell shield, because her dash is on a lower cooldown than the shield.
Le Blanc's Passive allows to remain invisible for a short period and spawn a clone.
Having a true sight item is important here because a Le Blanc at this stage has used all her abilities and completely on cooldown. This period buys her an extra second which is very important, by using true sight you can take this precious time away from her and strike her down.
Allow True Sight.
For the best opposition to Le Blanc, I'd personally choose either Talon or Twisted Fate. There is some degree of skill involved in laning Le Blanc to avoid being Q-R'd to death.