Missy, Altar of Dementia, and Horde Ambusher

Prerequisites

• Missy on the battlefield
• Altar of Dementia on the battlefield
• Horde Ambusher on the battlefield
• You have at least one red card in hand

Steps

1. Activate Altar of Dementia by sacrificing Horde Ambusher
2. When Horde Ambusher dies, Missy's first ability triggers, returning Horde Ambusher from your graveyard to the battlefield face down as a 2/2 Cyberman artifact creature
3. Resolve the Altar of Dementia ability, causing target player to mill cards equal to Horde Ambusher's power
4. Activate Horde Ambusher's morph ability by revealing a red card from your hand, turning it face up
5. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill