Tazri, Stalwart Survivor, Gilder Bairn, and Biomancer's Familiar

Prerequisites

• Tazri, Stalwart Survivor on the battlefield
• Gilder Bairn on the battlefield
• Biomancer's Familiar on the battlefield
• Gilder Bairn does not have summoning sickness

Steps

1. Activate Gilder Bairn by tapping it, adding that can only be spent to activate abilities
2. Activate Gilder Bairn by paying and untapping it, doubling each counter on target permanent
3. Repeat

Results

• Infinite proliferate