Mortuary, Bolas's Citadel, Goblin Firestarter, and Arnyn, Deathbloom Botanist

Prerequisites

• Mortuary on the battlefield
• Bolas's Citadel on the battlefield
• Goblin Firestarter in hand
• Arnyn, Deathbloom Botanist on the battlefield

Steps

1. Cast Goblin Firestarter by paying its mana cost
2. Activate Goblin Firestarter by sacrificing it
3. When Goblin Firestarter dies, Mortuary and Arnyn trigger
4. Resolve the Mortuary trigger, putting Goblin Firestarter from your graveyard onto the top of your library
5. Resolve the Arnyn trigger, causing target opponent to lose 2 life and you to gain 2 life
6. Cast Goblin Firestarter from the top of your library by paying 1 life
7. Repeat from step 2

Results

• Infinite creature ETB
• Infinite creature LTB
• Infinite damage
• Infinite death triggers
• Infinite lifegain triggers
• Infinite lifeloss
• Infinite creature sacrifice triggers
• Infinite storm count