Firestorm Phoenix, Phyrexian Altar, Elvish Piper, and Intruder Alarm

Prerequisites

• Firestorm Phoenix in hand
• Phyrexian Altar on the battlefield
• Elvish Piper on the battlefield
• Intruder Alarm on the battlefield
• Elvish Piper does not have summoning sickness
• available

Steps

1. Activate Elvish Piper by paying and tapping it, putting Firestorm Phoenix onto the battlefield from your hand
2. When Firestorm Phoenix enters the battlefield, Intruder Alarm triggers, untapping all creatures
3. Activate Phyrexian Altar by sacrificing Firestorm Phoenix, adding
4. Firestorm Phoenix is returned to your hand instead of being put into your graveyard
5. Repeat

Results

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