At any time during a performance, a spectator from the crowd (or online conference application of choice) is invited to take on the role of "acting magician". The performer then becomes the "spectator"; a reversal of roles. Using their VERY OWN mobile phone the "Acting Magician" conducts a feat of mentalism with the help of the magician, acting as a spectator.
The newly appointed ACTING MAGICIAN simply navigates through the screens presented by the app, instructing the ACTING SPECTATOR how to proceed in a mind-blowing card prediction. After a series of acting back and forth between magician and spectator (does it really matter who's who at this point?) the ACTING MAGICIAN reveals the prediction. The ACTING SPECTATOR shows the card matches. The audience goes wild. The ACTING MAGICIAN goes back to their seat as the spectator. Then they go home after the act wondering how they did it and unable to explain this newfound power to their friends.
The effect starts clean and ends clean. You (the performer) have very little work because the app is essentially self-working and the spectator takes on all the necessary activity.