Miirym, Sentinel Wyrm, and Changeling Titan

Prerequisites

• Miirym, Sentinel Wyrm on the battlefield
• Changeling Titan in hand
• available

Steps

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

Results

• Infinite ETB
• Infinite LTB