Ashnod's Altar, Felidar Guardian, and Sister Hospitaller

Prerequisites

• Ashnod's Altar on the battlefield
• Felidar Guardian in hand
• Sister Hospitaller on the battlefield
• available

Steps

1. Cast Felidar Guardian by paying its mana cost
2. When Felidar Guardian enters the battlefield, it triggers, targeting Sister Hospitaller Holding priority, activate Ashnod's Altar by sacrificing Felidar Guardian
3. Resolve the Felidar Guardian ability, blinking Sister Hospitaller When Sister Hospitaller enters, it triggers, returning Felidar Guardian from your graveyard to the battlefield and causing you to gain 4 life
4. Repeat from step 2

Results

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