Worldgorger Dragon, Changeling Titan, and Mardu Siegebreaker

Prerequisites

• Worldgorger Dragon in hand or on the battlefield or in exile
• Changeling Titan 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 Worldgorger Dragon for its mana cost
2. When Worldgorger Dragon enters, it exiles Changeling Titan until Worldgorger Dragon leaves the battlefield
3. Resolve any additional effects of Worldgorger Dragon's ETB
4. When Changeling Titan leaves the battlefield, Mardu Siegebreaker is returned from exile to the battlefield
5. When Mardu Siegebreaker enters, it exiles Worldgorger Dragon until Mardu Siegebreaker leaves the battlefield
6. Resolve any additional effects of Mardu Siegebreaker's ETB
7. When Worldgorger Dragon leaves the battlefield, Changeling Titan is returned from exile to the battlefield
8. When Changeling Titan enters, it exiles Mardu Siegebreaker until Changeling Titan leaves the battlefield
9. Resolve any additional effects of Changeling Titan's ETB
10. When Mardu Siegebreaker leaves the battlefield, Worldgorger Dragon is returned from exile to the battlefield
11. Repeat from step 2

Results

• Infinite creature ETB
• Infinite creature LTB
• Infinite blinking of permanents
• Infinite mana lands you control can produce