Requires

Miirym, Sentinel Wyrm must be on the battlefield. Glasspool Mimic // Glasspool Shore 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 Glasspool Mimic.
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 Glasspool Mimic from exile to the battlefield as a copy of the Changeling Berserker token.
7. Glasspool Mimic enters the battlefield, triggering its champion ability and Miirym.
8. Resolve the Glasspool Mimic 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 Glasspool Mimic that can copy any creatures you control.

Results