Gilder Bairn, Agatha's Soul Cauldron, and Overgrown Battlement

Prerequisites

• Gilder Bairn in exile
• Agatha's Soul Cauldron on the battlefield
• Overgrown Battlement on the battlefield

Steps

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

Results

• Infinite green mana
• Infinite proliferate