Activate Thermopod's second ability by sacrificing Eternal Witness, adding .
When Eternal Witness dies, Mortuary triggers, putting Eternal Witness on top of your library from your graveyard.
Cast Hit the Mother Lode by paying 4, exiling Eternal Witness from the top of your library and casting it without paying its mana cost, and creating seven tapped Treasure artifact tokens.
When Eternal Witness and the Treasures enter the battlefield, Amulet of Vigor triggers seven times and Eternal Witness triggers once.
Resolve all Amulet of Vigor triggers, untapping the Treasures.
Resolve the Eternal Witness trigger, returning Hit the Mother Lode from your graveyard to your hand.
Activate six Treasures by tapping and sacrificing them, adding 4.
Repeat.
This explosive loop relies on chaining Hit the Mother Lode into Eternal Witness to endlessly farm treasures and mana. When you sacrifice Eternal Witness to Thermopod, Mortuary immediately intervenes to stack it right back onto your library, perfectly positioned for Hit the Mother Lode's Discover 10 mechanic to cast it for free while minting a massive surplus of tapped Treasure tokens. Thanks to Amulet of Vigor, those treasures enter the battlefield ready to be immediately cracked for mana alongside Thermopod's sacrifice outlet, while Eternal Witness recovers the spell from your graveyard to keep the engine roaring forever.