Mikaeus, the Unhallowed, Medicine Runner, and Phyrexian Altar

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Medicine Runner on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Sacrifice Medicine Runner to make a mana of any color
2. Return it with the undying trigger
3. Using it's ability remove the +1/+1 counter from Medicine Runner
4. Repeat

Results

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