Szarel, Genesis Shepherd, and Yahenni, Undying Partisan

Prerequisites

• Szarel, Genesis Shepherd on the battlefield
• Yahenni, Undying Partisan on the battlefield

Steps

1. Activate Yahenni by sacrificing a persist creature without a -1/-1 counter on it
2. When the persist creature dies, its persist ability and Szarel trigger
3. Resolve the Szarel trigger, putting a number of +1/+1 counters on the other persist creature
4. Resolve the perist creature's trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it
5. Resolve the Yahenni ability
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers