Mikaeus, the Unhallowed, Cauldron of Souls, Intruder Alarm, Animate Artifact, and Altar of Dementia

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Cauldron of Souls on the battlefield
• Intruder Alarm on the battlefield
• Animate Artifact on the battlefield
• Altar of Dementia on the battlefield
• You control at least one additional nontoken non-Human creature
• Animate Artifact attached to Cauldron of Souls
• Cauldron of Souls does not have summoning sickness

Steps

1. Activate Altar of Dementia by sacrificing the additional nontoken non-Human creature
2. When the creature dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures
4. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power
5. Activate Cauldron of Souls by tapping it, giving the creature persist until end of turn
6. Activate Altar of Dementia by sacrificing the creature
7. When the creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
8. When the creature enters the battlefield, Intruder Alarm triggers, untapping all creatures
9. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power
10. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill
• Infinite untap of all creatures