Boommobile, The Prydwen, Steel Flagship, and Emiel the Blessed

Prerequisites

• Boommobile on the battlefield
• The Prydwen, Steel Flagship on the battlefield
• Emiel the Blessed on the battlefield

Steps

1. Activate Boommobile's crew ability by tapping Emiel, causing Boommobile to become an artifact creature until end of turn
2. Activate Emiel by paying , blinking Boommobile
3. When Boommobile enters the battlefield, it and The Prydwen trigger
4. Resolve the Prydwen trigger, creating a 2/2 Human Knight creature token
5. Resolve the Boommobile trigger, adding four mana of any color that can only be spent to activate abilities
6. Activate Boommobile's crew ability by tapping the Human Knight, causing Boommobile to become an artifact creature until end of turn
7. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite damage
• Infinite tapped creature tokens
• Infinite colored mana that can only be spent to activate abilities
• Infinite +1/+1 counters on a creature