Further considering invisibility mechanics in League of Legends, Vayne's Night Hunter innate ability increases her move speed when moving toward an enemy. I'm pretty sure champions beyond the fog of war are out of range, and the movement bonus no longer applies. (for instance, if someone flashes out of sight, you won't be moving faster than normal anymore)
I have not seen/heard about what happens if Vayne is running toward an invisible enemy. Will she continue to receive a movement bonus even if she cannot see her invisible foe?