Mortuary, Carmen, Cruel Skymarcher, Bolas's Citadel, and Accursed Centaur

Prerequisites

• Mortuary on the battlefield
• Carmen, Cruel Skymarcher on the battlefield
• Bolas's Citadel on the battlefield
• Accursed Centaur in hand
• available

Steps

1. Cast Accursed Centaur by paying its mana cost
2. Activate Accursed Centaur by sacrificing it
3. When Accursed Centaur dies, Mortuary and Carmen trigger
4. Resolve the Mortuary trigger, putting Accursed Centaur from your graveyard onto the top of your library
5. Resolve the Carmen trigger, causing you to gain at least 1 life
6. Cast Accursed Centaur from the top of your library by paying 1 life
7. Repeat from step 2

Results

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