Gilder Bairn, Agatha's Soul Cauldron, and Incubation Druid

Prerequisites

• Gilder Bairn in exile
• Agatha's Soul Cauldron on the battlefield
• Incubation Druid on the battlefield

Steps

1. Activate Incubation Druid by tapping it, adding
2. Activate Incubation Druid using Gilder Bairn's ability by paying and untapping it, doubling the counters on target permanent
3. Repeat

Results

• Infinite proliferate