Miirym, Sentinel Wyrm, Mirror Image, and Changeling Berserker

Prerequisites

• Miirym, Sentinel Wyrm on the battlefield
• Mirror Image on the battlefield
• Changeling Berserker in hand
• available

Steps

1. Cast Changeling Berserker by paying
2. Changeling Berserker enters the battlefield, triggering its champion ability and Miirym
3. Resolve the Changeling Berserker trigger, championing Mirror Image
4. Resolve the Miirym trigger, creating a copy of Changeling Berserker
5. The token Changeling Berserker enters the battlefield, championing the nontoken Changeling Berserker
6. The nontoken Changeling Berserker leaves the battlefield, returning Mirror Image from exile to the battlefield as a copy of the Changeling Berserker token
7. Mirror Image enters the battlefield, triggering its champion ability and Miirym
8. Resolve the Mirror Image trigger, championing the token Changeling Berserker
9. The token Changeling Berserker leaves the battlefield, returning the nontoken Changeling Berserker from exile to the battlefield
10. Repeat from step 2
11. Resolve all remaining Miirym triggers, creating infinite nonlegendary copies of Mirror Image that can copy any creatures you control

Results

• Infinite copies of creatures you control
• Infinite creature tokens
• Infinite ETB
• Infinite LTB