Retreat to Emeria, Haru, Hidden Talent, and Riveteers Overlook

Prerequisites

• Retreat to Emeria on the battlefield
• Haru, Hidden Talent on the battlefield
• Riveteers Overlook in hand

Steps

1. Play Riveteers Overlook
2. When Riveteers Overlook 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 Riveteers Overlook
5. Resolve the Riveteers Overlook trigger from step 2, causing you to sacrifice it, search your library for an applicable land and put it onto the battlefield tapped, and gain 1 life
6. Haru triggers, returning Riveteers Overlook from your graveyard to the battlefield
7. Repeat from step 2

Results

• Infinite ETB
• Infinite lifegain triggers
• Infinite lifegain
• Infinite creature tokens
• Near-infinite landfall triggers
• Infinite landfall triggers
• Put all basic Mountains from your library onto the battlefield tapped
• Put all basic Forests from your library onto the battlefield tapped
• Put all basic Swamps from your library onto the battlefield tapped