Chthonian Nightmare and Greedy Freebooter on the battlefield.
You have at least three energy counters.
Steps
Activate Chthonian Nightmare by paying ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) , sacrificing Greedy Freebooter and returning Chthonian Nightmare from the battlefield to your hand.
When Greedy Freebooter dies, it triggers, creating a Treasure token and causing you to scry 1.
Resolve the Chthonian Nightmare ability, returning Priest of Gix from your graveyard to the battlefield.
When Priest of Gix enters the battlefield, it triggers, adding ({B} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Activate the Treasure by tapping and sacrificing it, adding ({1} 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) , sacrificing Priest of Gix and returning Chthonian Nightmare from the battlefield to your hand, returning Greedy Freebooter from your graveyard to the battlefield.