Missy, Skirk Alarmist, Thornbite Staff, and Phyrexian Altar

Prerequisites

• Missy on the battlefield
• Skirk Alarmist on the battlefield
• Thornbite Staff on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing another nontoken nonartifact creature, adding one mana of any color
2. When the creature dies, Missy's first ability and Skirk Alarmist trigger
3. Resolve the Missy ability, returning the creature from your graveyard to the battlefield face down as a 2/2 Cyberman artifact creature
4. Resolve the Skirk Alarmist trigger, untapping it
5. Activate Skirk Alarmist by tapping it, turning the creature face up
6. Repeat

Results

• Infinite colored mana
• Infinite death triggers
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers