Vayne's Flaw
Although Vayne is a very powerful adc she has one big flaw. I think that the simple addition of a "flare," attached to her condemn ability would just make sense. For example, this "flare" would come into play when you successfully nail an enemy champion to a wall. Granting you vision of said champion until the stun wears off. Making Vayne's well aimed shot a more viable option, especially in the early game phase when the majority of the outside lane wall is covered in brush.