Mortuary, Carmen, Cruel Skymarcher, Bolas's Citadel, and Spore Frog

Prerequisites

• Mortuary on the battlefield
• Carmen, Cruel Skymarcher on the battlefield
• Bolas's Citadel on the battlefield
• Spore Frog on the battlefield

Steps

1. Activate Spore Frog by sacrificing it
2. When Spore Frog dies, Mortuary and Carmen trigger
3. Resolve the Mortuary trigger, putting Spore Frog from your graveyard onto the top of your library
4. Resolve the Carmen trigger, causing you to gain 1 life and put a +1/+1 counter on Carmen
5. Resolve the Spore Frog ability
6. Cast Spore Frog from the top of your library by paying 1 life
7. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite lifegain triggers
• Infinite sacrifice triggers
• Infinite storm count