Omarthis, Ghostfire Initiate, Mirage Mirror, Vanquisher's Banner, and Mirror Gallery

Prerequisites

• Omarthis, Ghostfire Initiate on the battlefield
• Mirage Mirror on the battlefield
• Vanquisher's Banner on the battlefield
• Mirror Gallery on the battlefield
• You have a way to put a +1/+1 counter on a colorless creature you control
• "Spirit" or "Snake" chosen with Vanquisher's Banner
• available

Steps

1. Put a +1/+1 counter on a colorless creature you control
2. Omarthis's first triggered ability triggers
3. In response, activate Mirage Mirror by paying , causing it to become a copy of Omarthis until end of turn
4. Resolve the Omarthis trigger, putting a +1/+1 counter on itself
5. Mirage Mirror triggers, putting a +1/+1 counter on itself
6. Omarthis triggers, putting a +1/+1 counter on itself
7. Repeat from step 5 any number of times
8. End the loop by declining to place a +1/+1 counter on a creature
9. Warning: Omarthis's last ability can increase the risk of losing by drawing from an empty library if you place enough counters on them

Results

• Infinite +1/+1 counters on Omarthis and Mirage Mirror