Vedalken Mastermind, Intruder Alarm, Dual Nature, Phyrexian Altar, and Ornithopter

Prerequisites

• Vedalken Mastermind on the battlefield
• Intruder Alarm on the battlefield
• Dual Nature on the battlefield
• Phyrexian Altar on the battlefield
• Ornithopter in hand
• Vedalken Mastermind does not have summoning sickness

Steps

1. Cast Ornithopter by paying
2. When Ornithopter enters the battlefield, Intruder Alarm and Dual Nature's first ability triggers
3. Resolve the Intruder Alarm trigger, untapping all creatures
4. Resolve the Dual Nature trigger, creating a token copy of Ornithopter
5. Activate Phyrexian Altar by sacrificing the Ornithopter token, adding
6. Activate Vedalken Mastermind by paying and tapping it, returning Ornithopter to your hand from the battlefield
7. Dual Nature's second ability triggers, exiling nothing
8. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite storm count
• Infinite untap of all creatures