Chthonian Nightmare and Pitiless Plunderer on the battlefield.
You have at least ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) .
You control a nontoken creature with mana value 3 or less.
Steps
Activate Chthonian Nightmare by paying ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) , sacrificing a creature with mana value 3 or less and returning Chthonian Nightmare from the battlefield to your hand.
When the creature dies, Pitiless Plunderer triggers, creating a Treasure token.
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 at most ({E} magic symbol) ({E} magic symbol) ({E} magic symbol) , sacrificing Priest of Gix and returning Chthonian Nightmare from the battlefield to your hand.
When Priest of Gix dies, Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Chthonian Nightmare ability, returning another creature with mana value 3 or less from your graveyard to the battlefield.