If you are looking for an incredibly powerful closer to your ambitious card routine, here it is. This is amazing visual magic that will literally take the breath away of your audience. In the video this is presented as a sort of stand-alone trick, but I've found it plays much better as part of a routine like ambitious card. A signed card lost in the deck, the deck put back into the case, the case is dropped onto the table or a spectator's hands, and the signed card is on the outside of the case in a rubber band...it gets them every time.
You will need to practice the clean up move just a little, but it's not that hard to do. I have yet to see a spectator who reaches for the case after I extract the card. They always want to examine the card itself, which is perfect because it allows me to clean up without their knowledge.
The prop will eventually wear out and you probably aren't going to be able to make one yourself, but you'll get a lot of magic out of it before it dies.
Very visual and fairly easy to work with.