[GAMEPLAY] Stunning a low HP Leblanc with her passive ready makes her go 'poof!'

I have noticed recently that while playing Annie, if I stun Leblanc while she has her passive ready to be used and is low health enough, she will use the passive while stunned and stay invisible during the stun, making me unable to hit her at all for nearly two (2) seconds. I'm not sure if this is the intended behavior, but it seems rather overpowered to me.

The bug can be reproduced by:

1. Attacking Leblanc until your next stun gets her below the threshold for her passive ability to activate;
2. Stunning Leblanc with an ability, making her activate her passive ability;
3. Watching her go 'poof!' for the duration of your stun, plus the time her passive takes to visually process;
4. Get rekt like a nab and rage quit.