Hullbreaker Horror + Memnite + Ornithopter

Hullbreaker Horror
Memnite
Ornithopter

Requires
Memnite in hand. All other permanents on the battlefield.
Steps
  1. Cast Memnite by paying 0
  2. Hullbreaker Horror triggers, returning Ornithopter from the battlefield to your hand
  3. Cast Ornithopter by paying 0
  4. Hullbreaker Horror triggers, returning Memnite from the battlefield to your hand
  5. Repeat
Results
Infinite ETB. Infinite LTB. Infinite storm count.