Gilder Bairn, Agatha's Soul Cauldron, and Rainveil Rejuvenator

Prerequisites

• Gilder Bairn in exile
• Agatha's Soul Cauldron on the battlefield
• Rainveil Rejuvenator on the battlefield

Steps

1. Activate Rainveil Rejuvenator by tapping it, adding at least Activate Rainveil Rejuvenator using Gilder Bairn's ability by paying and untapping it, doubling the counters on target permanent
2. Repeat

Results

• Infinite green mana
• Infinite proliferate