Concept: While the magician is performing his act, the spectator can flip at any time one of the 5 face down cards laying on the table, revealing a Cardistry move the magician has to incorporate in his show.
Credit: Harapan Ong and his card game.
The other way around would be for the cardists to be executing a routine of his move, and then one of his friends turns a card face up and he is to incorporate that sleight/effect into his routine.
This reminds me of a Dan and Dave contest from years ago when cardists were challenged to come up with a cut which incorporated a color change. The best example of this which I know is Aviv's Disappearing Queen.