Umbral Mantle, and Selvala, Eager Trailblazer

Prerequisites

• Umbral Mantle on the battlefield
• Selvala, Eager Trailblazer on the battlefield

Steps

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

Results

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