Mardu Siegebreaker, and Éomer, Marshal of Rohan

Prerequisites

• Mardu Siegebreaker on the battlefield
• Éomer, Marshal of Rohan in exile
• available

Steps

1. Declare Mardu Siegebreaker as an attacker, triggering its second ability, creating at least two token copies of Éomer that is tapped and attacking
2. Put all but one Éomer token into your graveyard due to the legend rule
3. When the Éomer token(s) die, you will get at least one Éomer trigger, causing you to untap all creatures you control and to get an additional combat phase after this one
4. Repeat each combat phase

Results

• Infinite LTB
• Infinite ETB
• Infinite death triggers
• Infinite combat phases
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce