Redshift, Rocketeer Chief, and Umbral Mantle

Prerequisites

• Redshift, Rocketeer Chief on the battlefield
• Umbral Mantle on the battlefield
• undefined at most available

Steps

1. Activate Redshift by tapping it, adding an amount mana of any color equal to its power that can only be spent to activate abilities
2. Activate Redshift by paying and untapping it, giving it +2/+2 until end of turn
3. Repeat

Results

• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinite power and toughness for a creature until end of turn
• Infinite colored mana that can only be spent to activate abilities