Blackjack Double Deception by Dustin Marks

The two black aces visually change places with the two red aces and then instantly change into two Blackjacks.

Great Opener: A lot of visual magic happens in 30 seconds
Simplicity: Only four cards are used; easy to do; no table is needed; packs very small
Impact: Surprise ending
Practicality: 2-second reset; perfect for table hopping
Spectator Engagement: The spectator just watches, no picking a card, no remembering anything; just visual magic
One Simple Move: The Flustration Count