Phenax, God of Deception, The Walls of Ba Sing Se, and Umbral Mantle

Prerequisites

• Phenax, God of Deception on the battlefield
• The Walls of Ba Sing Se on the battlefield
• Umbral Mantle on the battlefield
• at least available

Steps

1. Activate The Walls of Ba Sing Se by tapping it, causing a player to mill at least thirty cards
2. Activate The Walls of Ba Sing Se by paying and untapping it, giving it +2/+2 until end of turn
3. Repeat as mana allows

Results

• Near-infinite mill
• Near-infinite self-mill