Chthonian Nightmare and Patron of the Arts on the battlefield.
You have at least ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) .
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 Burning-Tree Emissary from your graveyard to the battlefield.
When Burning-Tree Emissary enters the battlefield, it triggers, adding ({R} magic symbol) ({G} magic symbol) .
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 Burning-Tree Emissary and returning Chthonian Nightmare from the battlefield to your hand, 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) .