Hi,
Not a bug but I'm not sure where to submit feedback of this kind.
Whenever I get hit by Liliana of the Veil 's -6 ability, I can never remember which pile is sacrificed and which pile is not. But when the "Choose a pile" dialogue comes up, I am unable to mouse-over the card to see which it is. Could you change the "Choose a pile" dialogue box header to say "Choose a pile to be sacrificed" to make it more clear?