Changeling Titan, Hostage Taker, and Lumbering Battlement

Prerequisites

• Changeling Titan in hand or on the battlefield or in exile
• Hostage Taker in hand or on the battlefield or in exile
• Lumbering Battlement 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 Hostage Taker until Changeling Titan leaves the battlefield
3. Resolve any additional effects of Changeling Titan's ETB
4. When Hostage Taker leaves the battlefield, Lumbering Battlement is returned from exile to the battlefield
5. When Lumbering Battlement enters, it exiles Changeling Titan until Lumbering Battlement leaves the battlefield
6. Resolve any additional effects of Lumbering Battlement's ETB
7. When Changeling Titan leaves the battlefield, Hostage Taker is returned from exile to the battlefield
8. When Hostage Taker enters, it exiles Lumbering Battlement until Hostage Taker leaves the battlefield
9. Resolve any additional effects of Hostage Taker's ETB
10. When Lumbering Battlement leaves the battlefield, Changeling Titan is returned from exile to the battlefield
11. Repeat from step 2

Results

• Infinite creature ETB
• Infinite creature LTB