Mairsil, the Pretender, Blood Vassal, Endling, and Spike Feeder

Prerequisites

• Mairsil, the Pretender on the battlefield
• Blood Vassal in exile
• Endling in exile
• Spike Feeder in exile
• Mairsil does not have a +1/+1 counter on it
• available

Steps

1. Activate Mairsil using Endling's third ability by paying , giving Mairsil undying until end of turn
2. Activate Mairsil using Blood Vassal's ability by sacrificing it, adding
3. Mairsil dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
4. Activate Mairsil using Spike Feeder's second ability by removing a +1/+1 counter from it, causing you to gain 2 life
5. Repeat

Results

• Infinite black mana
• Infinite death triggers
• Infinite ETB
• Infinite lifegain
• Infinite lifegain triggers
• Infinite LTB
• Infinite sacrifice triggers