Steward of the Harvest, Umbral Mantle, and Gaea's Cradle

Prerequisites

• Steward of the Harvest on the battlefield
• Umbral Mantle on the battlefield
• Gaea's Cradle in exile

Steps

1. Activate the creature with Umbral Mantle attached using Gaea's Cradle's ability by tapping it, adding at least
2. Activate the creature by paying and untapping it, giving it +2/+2 until end of turn
3. Repeat

Results

• Infinite green mana
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinitely large creature until end of turn