Rubinia Soulsinger, Requiem Angel, Intruder Alarm, and Altar of Dementia

Prerequisites

• Rubinia Soulsinger on the battlefield
• Requiem Angel on the battlefield
• Intruder Alarm on the battlefield
• Altar of Dementia on the battlefield
• Rubinia Soulsinger does not have summoning sickness

Steps

1. Activate Rubinia Soulsinger by tapping it, causing you to gain control of target non-Spirit creature an opponent controls for as long as Rubinia Soulsinger is tapped
2. Activate Altar of Dementia by sacrificing the creature
3. When the creature dies, Requiem Angel triggers, creating a 1/1 Spirit creature token
4. When the Spirit enters the battlefield, Intruder Alarm triggers, untapping all creatures
5. Resolve the Altar of Dementia ability from step 2, causing target player to mill cards equal to the sacrificed creature's power
6. Repeat as desired
7. You may also repeat this combo whenever a creature enters the battlefield under an opponent's control, and retain control of that creature until Rubinia Soulsinger would become untapped

Results

• Gain control of any creature that enters the battlefield