Umbral Mantle, and Axebane Guardian

Prerequisites

• Umbral Mantle on the battlefield
• Axebane Guardian on the battlefield
• undefined

Steps

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

Results

• Infinite power for a creature until end of turn
• Infinite colored mana