Intruder Alarm, Krark-Clan Ironworks, Myr Battlesphere, and Othelm, Sigardian Outcast

Prerequisites

• Intruder Alarm on the battlefield
• Krark-Clan Ironworks on the battlefield
• Myr Battlesphere on the battlefield
• Othelm, Sigardian Outcast on the battlefield
• Othelm does not have summoning sickness

Steps

1. Activate Krark-Clan Ironworks by sacrificing Myr Battlesphere, adding
2. Activate Othelm by paying and tapping it, returning Myr Battlesphere from your graveyard to the battlefield tapped
3. Myr Battlesphere enters the battlefield, triggering itself and Intruder Alarm
4. Resolve the Intruder Alarm trigger, untapping all creatures
5. Resolve the Myr Battlesphere trigger, creating four 1/1 Myr artifact creature tokens
6. The Myr tokens enter the battlefield, triggering Intruder Alarm four times, untapping all creatures
7. Repeat

Results

• Infinite colorless mana
• Infinite creature tokens
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite tap triggers
• Infinite untap of all creatures