New Lissandra passive

I have been playing Lissandra on my alt lately and have been having some issues with her passive. It seems to be a placeholder for what could be something better. I noticed that it takes much more than other mages to get her going and this is due to a few things. Her low range on her Q which is fine on its own but hurts her because of its lack of damage and mana cost. The point of her passive is to poke our opponent down in lane before you all in at 6 and up. The problem is that she uses too much mana during this time and the passive dose little to help. So I thought of a new passive.

For each minon and nutral monster killed Lissandra's base mana pool incresses by 5 and she gains .6 bonus Ap

Its just an idea.