Chthonian Nightmare, Patron of the Arts, and Rowan, Scion of War

Prerequisites

• Chthonian Nightmare on the battlefield
• Patron of the Arts on the battlefield
• Rowan, Scion of War on the battlefield

Steps

1. Activate Rowan by tapping it, causing black and red spells you cast to cost less for each life you've lost this turn
2. Activate Chthonian Nightmare by paying at most , sacrificing Patron of the Arts and returning Chthonian Nightmare from the battlefield to your hand
3. When Patron of the Arts dies, it triggers, creating a Treasure token
4. Resolve the Chthonian Nightmare ability, returning another creature card from your graveyard to the battlefield
5. Activate the Treasure by tapping and sacrificing it, adding
6. Cast Chthonian Nightmare by paying
7. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get
8. Activate Chthonian Nightmare by paying , sacrificing another creature and returning Chthonian Nightmare from the battlefield to your hand, returning Patron of the Arts from your graveyard to the battlefield
9. When Patron of the Arts enters the battlefield, it triggers, creating a Treasure token
10. Activate the Treasure by tapping and sacrificing it, adding
11. Cast Chthonian Nightmare by paying
12. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get
13. Repeat from step 2

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite energy counters
• Infinite sacrifice triggers
• Infinite storm count