Miirym, Sentinel Wyrm + Changeling Titan

Prerequisites

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Steps

1. 1Cast Changeling Titan by paying its mana cost.
2. 2When Changeling Titan enters, its champion ability and Miirym trigger.
3. 3Resolve the Miirym trigger, creating a token copy of Changeling Titan.
4. 4When the Changeling Titan token enters, its champion ability triggers, exiling the nontoken Changeling Titan until the token Changeling Titan leaves the battlefield.
5. 5Resolve the Changeling Titan trigger from step 2, exiling the token Changeling Titan.
6. 6The token Changeling Titan leaves the battlefield, returning the nontoken Changeling Titan from exile to the battlefield.
7. 7Repeat from step 2.

Effects

• Infinite creature ETB
• Infinite creature LTB