Requires

Miirym, Sentinel Wyrm must be on the battlefield. Phantasmal Image must be on the battlefield. Changeling Berserker must be in hand. Mana needed:

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 Phantasmal 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 Phantasmal Image from exile to the battlefield as a copy of the Changeling Berserker token.
7. Phantasmal Image enters the battlefield, triggering its champion ability and Miirym.
8. Resolve the Phantasmal 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 Phantasmal Image that can copy any creatures you control.

Results