Gideon of the Trials, Magus of the Mirror, and Cavern Harpy

Prerequisites

• Gideon of the Trials on the battlefield
• Magus of the Mirror on the battlefield
• Cavern Harpy on the battlefield
• You have earned Gideon's emblem

Steps

1. During your upkeep, activate Cavern Harpy by paying 1 life
2. Repeat step 1 until you have zero life
3. Resolve the last Cavern Harpy trigger, returning it to your hand
4. The remaining Cavern Harpy triggers fizzle
5. Activate Magus of the Mirror by tapping and sacrificing it, exchanging your life total with an opponent
6. The opponent loses the game due to having zero life

Results

• Target player loses the game