This feels so satisfying. Really great feeling card mechanic with the dragging/reorganizing. I think a "feature that would be nice to add" would be something like an area on the table where the card can be placed a bit messy. For example in your game Sacrifice, when you drag the card over to the play area, it will just drop right on the center in a nice neat stack. But if you have some margin for a bit left or a bit right of the stack, it would really add to the feeling of "I placed this card there".
Plus, having a play area capability would generally help with the tool since you almost always need one in a card game like this. Less overhead for the developer looking for this kind of tool, yknow?