Activate Ashnod's Altar by sacrificing Eternal Witness, adding CC.
When Eternal Witness dies, Pitiless Plunderer triggers, creating a Treasure artifact token.
Activate the Treasure by tapping and sacrificing it, adding .
Activate Doomed Necromancer by paying , tapping it and sacrificing it.
When Doomed Necromancer dies, Pitiless Plunderer triggers, creating a Treasure artifact token.
Resolve the Doomed Necromancer ability, returning Eternal Witness from your graveyard to the battlefield.
When Eternal Witness enters the battlefield, it triggers, returning Doomed Necromancer from your graveyard to your hand.
Activate a Treasure by tapping and sacrificing it, adding .
Cast Doomed Necromancer by paying 2.
Repeat.
This clever loop lets you endlessly recur your graveyard while generating a surplus of mana through careful recycling. By using Ashnod's Altar to sacrifice Eternal Witness, you fund the black mana needed for Doomed Necromancer's revival ability—a loop tightly cushioned by Pitiless Plunderer, which reliably kicks off a Treasure token every time a creature bites the dust to keep the mana flowing. While Garna, the Bloodflame isn't strictly required to execute this specific core loop, its presence in the card pool rounds out graveyard strategies by ensuring fallen allies can easily find their way back to your hand when things get chaotic.