The possibility of going in AND out with the same spell is possibly the worst thing you can give to an assassin.

Most skillshots aren't fast enough to catch a Leblanc W'ing forward to QRE and oneshot your carry before. She can't be punished even when she jumps into 5 people during a siege unless you have an instant silence (pretty much only Soraka and Blitzcrank).

She also can't be chased because of how short her W and R cooldowns are and she is very very hard to gank.

Now, i know people will downvote me into oblivion for this but here are some possible ways to add some risk to her kit.

• Make the W-back a dash (like when she goes forward) instead of a blink to add more chance for skillshots to hit Leblanc when she is on the way back.

• Make subsequent Ws cost more mana (see Kassadin) or have more cooldown so that she can't chase people forever and she can't escape chases forever.

• Make her W have longer cooldown if it doesn't hit an enemy champion (see Gragas) to limit her chase and escape potential.