Umbral Mantle, and Deathbloom Ritualist

Prerequisites

• Umbral Mantle on the battlefield
• Deathbloom Ritualist on the battlefield

Steps

1. Activate Deathbloom Ritualist by tapping it, adding at least three mana of any color
2. Activate Deathbloom Ritualist by paying and untapping it, giving it +2/+2 until end of turn
3. Repeat

Results

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