Retreat to Emeria, Haru, Hidden Talent, and Crosis's Catacombs

Prerequisites

• Retreat to Emeria on the battlefield
• Haru, Hidden Talent on the battlefield
• Crosis's Catacombs in hand

Steps

1. Play Crosis's Catacombs
2. When Crosis's Catacombs enters, it and Retreat to Emeria trigger
3. Resolve the Retreat to Emeria trigger, creating a 1/1 Kor Ally creature token
4. When the Kor Ally enters, Haru triggers, earthbending Crosis's Catacombs
5. Resolve the Crosis's Catacombs trigger from step 2, causing you to sacrifice it Haru triggers, returning Crosis's Catacombs from your graveyard to the battlefield
6. Repeat from step 2

Results

• Infinite ETB
• Infinite lifegain triggers
• Infinite lifegain
• Infinite creature tokens
• Infinite landfall triggers