Ashcloud Phoenix, Skirk Alarmist, Intruder Alarm, and Phyrexian Altar

Prerequisites

• Ashcloud Phoenix on the battlefield
• Skirk Alarmist on the battlefield
• Intruder Alarm on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Ashcloud Phoenix, adding one mana of any color
2. When Ashcloud Phoenix dies, it triggers, returning itself from your graveyard to the battlefield face down
3. When Ashcloud Phoenix enters the battlefield, Intruder Alarm triggers, untapping all creatures
4. Activate Skirk Alarmist by tapping it, turning Ashcloud Phoenix face up
5. Repeat

Results

• Infinite colored mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of all creatures