Ashcloud Phoenix, Skirk Alarmist, Intruder Alarm, and Ashnod's Altar

Prerequisites

• Ashcloud Phoenix on the battlefield
• Skirk Alarmist on the battlefield
• Intruder Alarm on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Ashcloud Phoenix, adding
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 colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of all creatures