Dual Nature, and Faceless Butcher

Prerequisites

• Dual Nature on the battlefield
• Faceless Butcher in hand
• available

Steps

1. Cast Faceless Butcher by paying
2. Faceless Butcher enters the battlefield, triggering itself and Dual Nature's first ability
3. Resolve the Faceless Butcher trigger, choosing not to exile anything
4. Resolve the Dual Nature trigger, creating a token copy of Faceless Butcher
5. The token Faceless Butcher enters the battlefield, exiling the nontoken Faceless Butcher
6. Faceless Butcher leaves the battlefield, triggering Dual Nature's second ability, exiling the Faceless Butcher token
7. The Faceless Butcher token leaves the battlefield, triggering its second ability, returning the nontoken Faceless Butcher from exile to the battlefield
8. Repeat from step 2

Results

• Exile any target creatures
• Infinite ETB
• Infinite LTB
• Infinite triggers of ETB or LTB of any target creatures