Changeling Titan, Glorious Protector, and Mardu Siegebreaker

Prerequisites

• Changeling Titan in hand or on the battlefield or in exile
• Glorious Protector in hand or on the battlefield or in exile
• Mardu Siegebreaker in hand or on the battlefield or in exile
• plus the mana cost of the creature in your hand available

Steps

1. Cast Changeling Titan for its mana cost
2. When Changeling Titan enters, it exiles Glorious Protector until Changeling Titan leaves the battlefield
3. Resolve any additional effects of Changeling Titan's ETB
4. When Glorious Protector leaves the battlefield, Mardu Siegebreaker is returned from exile to the battlefield
5. When Mardu Siegebreaker enters, it exiles Changeling Titan until Mardu Siegebreaker leaves the battlefield
6. Resolve any additional effects of Mardu Siegebreaker's ETB
7. When Changeling Titan leaves the battlefield, Glorious Protector is returned from exile to the battlefield
8. When Glorious Protector enters, it exiles Mardu Siegebreaker until Glorious Protector leaves the battlefield
9. Resolve any additional effects of Glorious Protector's ETB
10. When Mardu Siegebreaker leaves the battlefield, Changeling Titan is returned from exile to the battlefield
11. Repeat from step 2

Results

• Infinite creature ETB
• Infinite creature LTB