Chthonian Nightmare and Patron of the Arts on the battlefield.
You have at least ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) .
({1} magic symbol) available.
Steps
Activate Chthonian Nightmare by paying ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) , sacrificing Patron of the Arts and returning Chthonian Nightmare from the battlefield to your hand.
When Patron of the Arts dies, it triggers, creating a Treasure token.
Resolve the Chthonian Nightmare ability, returning Cathodion from your graveyard to the battlefield.
Activate the Treasure by tapping and sacrificing it, adding ({B} magic symbol) .
When Chthonian Nightmare enters the battlefield, it triggers, causing you to get ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) .
Activate Chthonian Nightmare by paying ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) , sacrificing Cathodion and returning Chthonian Nightmare from the battlefield to your hand.
When Cathodion dies, it triggers, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .
Resolve the Chthonian Nightmare ability, returning Patron of the Arts from your graveyard to the battlefield.
When Patron of the Arts enters the battlefield, it triggers, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding ({B} magic symbol) .