[Gameplay] Cassiopeia Twin Fangs Invisible targets

I was playing Cassio against a LeBlanc. Whenever LeBlanc got low enough that her passive would pop I could continue using Twin Fang even while she was invisible. I am not sure if this works with other champs with invisibility or exactly how it works. My first though when it happened was Urgot and how his EQ work together on invisible targets as well(Although I am quite sure that is intentional.)

When a poisoned Target goes invisible you can continue using Twin Fang as Cass. (I had 18-12-0 Masteries with Deathfire touch)

I feel if left undealt with it could cause a lot of her "counter" play to be diminished(Alhtough I am still not sure it happens with all champs. Will continue testing with friends in custom)