Karn, Silver Golem, Chromatic Orrery, and Umbral Mantle

Prerequisites

• Karn, Silver Golem on the battlefield
• Chromatic Orrery on the battlefield
• Umbral Mantle on the battlefield
• Chromatic Orrery does not have summoning sickness

Steps

1. Activate Chromatic Orrery's first ability by tapping it, adding
2. Activate Karn by paying , causing Chromatic Orrery to become an artifact creature until end of turn
3. Activate Umbral Mantle's equip ability by paying , attaching it to Chromatic Orrery
4. Activate Chromatic Orrery by paying and untapping it, giving it +2/+2 until end of turn
5. Activate Chromatic Orrery's first ability by tapping it, adding
6. Repeat from step 4
7. Once you have infinite mana, you may instead use Chromatic Orrery's second ability if you control a colored permanent

Results

• Infinite card draw
• Infinite colored mana
• Infinite colorless mana
• Infinite draw triggers
• Infinitely large Chromatic Orrery until end of turn