LeBlanc invisible when attacking from fog of war!

I was playing Bard, and after a harrowing fight around the dragon pit, I escape by grabbing a chime and running through the scuttler's speed buff, effectively distancing myself from the pursuing enemies and managing to have 80% HP left. Then, when I'm almost to the safety of a jungle, my HP suddenly disappears and I'm dead, and there's LeBlanc, appearing beside me. There was nothing other than my instant death and her appearance near my corpse that told me I was being attacked. I didn't see any of her spells, particle effects, anything. She just launched it all from the fog and I was unable to do anything. This is a pretty large bug if it can be exploited, because LeBlanc is pretty nasty when you can see her, let alone when she's exploiting bugs to be completely invisible.