How to balance LeBlanc without gutting her

Remove the impact damage on Q. Simple as that. For someone with such low cooldowns, she doesn't need to be able to 500+ damage with just the Q without popping the Q proc. Her laning phase is strong enough as is so this wouldn't hurt that. This would also give the enemies a little breathing room because if they dodge both your W and E, they won't be on half health already. It would give her counterplay instead of her being completely dash chunk with just Q, return. Additionally, she would be forced to use her ult defensively in such a case as her ult version of W isn't enough to one-shot anyone. Pish posh with all this new stuff on PBE. LeBlanc's power is in how safe a pick she is with how high damage she is, so if you wanted to keep that around, making her not be able to just Q you 3 times to kill you would make her strictly an assassin instead of a mage with an escape.