Mortuary, Bolas's Citadel, Myr Scrapling, and Arnyn, Deathbloom Botanist

Prerequisites

• Mortuary on the battlefield
• Bolas's Citadel on the battlefield
• Myr Scrapling in hand
• Arnyn, Deathbloom Botanist on the battlefield

Steps

1. Cast Myr Scrapling by paying its mana cost
2. Activate Myr Scrapling by sacrificing it
3. When Myr Scrapling dies, Mortuary and Arnyn trigger
4. Resolve the Mortuary trigger, putting Myr Scrapling 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 Myr Scrapling from the top of your library by paying 1 life
7. Repeat from step 2

Results

• Infinite +1/+1 counters on creatures you control
• Infinite creature ETB
• Infinite creature LTB
• Infinite death triggers
• Infinite lifegain triggers
• Infinite lifeloss
• Infinite creature sacrifice triggers
• Infinite storm count