Mairsil, the Pretender, Endling, Blood Vassal, and Walking Ballista

Prerequisites

• Mairsil, the Pretender on the battlefield
• Endling in exile
• Blood Vassal in exile
• Walking Ballista in exile
• available

Steps

1. Activate Mairsil using Endling's third ability by paying , gaining Mairsil undying
2. Activate Mairsil using Blood Vassal's ability by sacrificing it, adding
3. Mairsil undying triggers, returning it to the battlefield with a +1/+1 counter
4. Activate Mairsil using Walking Ballista's last ability by removing a +1/+1 counter, dealing 1 damage to any target
5. Repeat

Results

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