You have sacrificed at least three artifacts and/or creatures this turn, plus an additional artifact or creature for each time you've cast Dargo from the command zone this game.
({R} magic symbol) available.
Steps
Cast Dargo from the command zone by paying ({R} magic symbol) .
Aetherflux Reservoir triggers, causing you to gain 1 life for each spell you've cast this turn.
Activate Razaketh by paying two life and sacrificing Dargo.
Choose to return Dargo to the command zone from your graveyard.
Pitiless Plunderer triggers, creating a Treasure token.
Resolve the Razaketh ability, causing you to search your library for a card and put it into your hand.
Activate the Treasure by tapping and sacrificing it, adding ({R} magic symbol) .
Repeat an arbitrarily large number of times.
Activate Aetherflux Reservoir by paying fifty life, dealing fifty damage to any target.