Rings of Brighthearth, Deserted Temple, and Matzalantli, the Great Door // The Core

Prerequisites

• Rings of Brighthearth on the battlefield
• Deserted Temple on the battlefield
• Matzalantli, the Great Door // The Core on the battlefield

Steps

1. Activate The Core by tapping it, adding at least four mana of any color
2. Activate Deserted Temple's second ability by paying and tapping it, targeting The Core
3. Rings of Brighthearth triggers, causing you to pay to copy Deserted Temple's ability, targeting Deserted Temple
4. Resolve both Deserted Temple abilities, untapping Deserted Temple and The Core Repeat

Results

• Infinite colored mana
• Infinite mana lands you control can produce
• Infinite untap of lands you control