Gilder Bairn, Song of Freyalise, and Biomancer's Familiar

Prerequisites

• Gilder Bairn on the battlefield
• Song of Freyalise on the battlefield
• Biomancer's Familiar on the battlefield
• Gilder Bairn does not have summoning sickness
• Song of Freyalise has exactly one or two lore counters on it

Steps

1. Activate Gilder Bairn by tapping it, adding
2. Activate Gilder Bairn by paying and untapping it, doubling each counter on target permanent
3. Repeat

Results

• Infinite proliferate