Requires

Molten Echoes must be on the battlefield (with any creature type chosen). Changeling Hero must be in hand. Mana needed:

Steps

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

Results