Gilder Bairn, Citanul Hierophants, and Training Grounds

Prerequisites

• Gilder Bairn on the battlefield
• Citanul Hierophants on the battlefield
• Training Grounds on the battlefield

Steps

1. Activate Gilder Bairn's ability from Citanul Hierophants by tapping it, adding
2. Activate Gilder Bairn by paying and untapping it, doubling each counter on target permanent
3. Repeat

Results

• Infinite proliferate for permanents