Szarel, Genesis Shepherd, Crystalline Crawler, Slimefoot and Squee, and Yahenni, Undying Partisan

Prerequisites

• Szarel, Genesis Shepherd on the battlefield
• Crystalline Crawler on the battlefield
• Slimefoot and Squee in the graveyard
• Yahenni, Undying Partisan on the battlefield
• available

Steps

1. Activate Slimefoot and Squee by paying and sacrificing a Saproling, returning it and up to one other creature card from your graveyard to the battlefield
2. When Slimefoot and Squee enters the battlefield, it triggers, creating a 1/1 Saproling creature token
3. Activate Yahenni by sacrificing Slimefoot and Squee, and the other creature returned in step 1, if applicable
4. When Slimefoot and Squee and up to one other creature are sacrificed, Szarel triggers that many times, putting a number of +1/+1 counters equal to Szarel's power on Crystalline Crawler for each trigger
5. Resolve the Yahenni abilities
6. Activate Crystalline Crawler four times by removing four +1/+1 counters from it, adding
7. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite colored mana
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite +1/+1 counters
• Infinite recursion of creature cards in your graveyard