Miirym, Sentinel Wyrm + Clone + Changeling Berserker

Miirym, Sentinel Wyrm

Clone

Changeling Berserker

How it works

1. Cast Changeling Berserker by paying 3.
2. Changeling Berserker enters the battlefield, triggering its champion ability and Miirym.
3. Resolve the Changeling Berserker trigger, championing Clone.
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 Clone from exile to the battlefield as a copy of the Changeling Berserker token.
7. Clone enters the battlefield, triggering its champion ability and Miirym.
8. Resolve the Clone 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 Clone that can copy any creatures you control.