Rings of Brighthearth, Deserted Temple, and Serra's Sanctum

Prerequisites

• Rings of Brighthearth on the battlefield
• Deserted Temple on the battlefield
• Serra's Sanctum on the battlefield

Steps

1. Activate Serra's Sanctum by tapping it, adding at least
2. Activate Deserted Temple's second ability by paying and tapping it, targeting Serra's Sanctum
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 Serra's Sanctum Repeat

Results

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