This is really amazing effect! ;)
Although it requires some preparation you need to to just once on your phone, the rest of the trick is impromptu - there is no card setup or anything like this ;)
What is essential for this card trick is to know how to do the Mercury card fold so if you don't know yet how this move is done, go ahead and check it out as well!
This will definitely require some practice but the result is well worth it!