Molten Echoes + Changeling Berserker

Molten Echoes
Changeling Berserker

Requires
Molten Echoes on the battlefield. Changeling Berserker in hand. Any creature type chosen with Molten Echoes. 3r available.
Steps
  1. Cast Changeling Berserker by paying 3r
  2. Changeling Berserker enters the battlefield, triggering itself and Molten Echoes
  3. Resolve the Molten Echoes trigger, creating a token copy of Changeling Berserker
  4. The Changeling Berserker token enters the battlefield, triggering itself, exiling the nontoken Changeling Berserker
  5. When the nontoken Changeling Berserker leaves the battlefield, it triggers itself, having no effect since no card was exiled
  6. Resolve the Changeling Berserker trigger from step 2, exiling the token Changeling Berserker
  7. When the token Changeling Berserker leaves the battlefield, it triggers itself, returning the nontoken Changeling Berserker from exile to the battlefield
  8. Repeat from step 2
Results
Infinite ETB. Infinite LTB.