Siona, Captain of the Pyleas, Reins of the Vinesteed, and Altar of Dementia

Prerequisites

• Siona, Captain of the Pyleas on the battlefield
• Reins of the Vinesteed in hand
• Altar of Dementia on the battlefield
• available

Steps

1. Cast Reins of the Vinesteed by paying , enchanting any Human or Soldier you control besides Siona
2. Siona triggers, creating a 1/1 Human Soldier creature token
3. Activate Altar of Dementia by sacrificing the creature enchanted by Reins of the Vinesteed
4. The creature dies, triggering Reins of the Vinesteed, returning Reins of the Vinesteed to the battlefield enchanting the Human Soldier token
5. Siona triggers, creating a 1/1 Human Soldier creature token
6. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power
7. Repeat from step 3

Results

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