Activate Ashnod's Altar by sacrificing Ornithopter, adding CC.
When Ornithopter dies, Sword of the Realms and Pitiless Plunderer trigger.
Resolve the Pitiless Plunderer trigger, creating a Treasure token.
Resolve the Sword of the Realms trigger, returning Ornithopter to your hand from your graveyard.
Cast Ornithopter by paying 0.
Activate the Treasure by tapping and sacrificing it, adding .
Activate Sword of the Realms' equip ability by paying 1, attaching it to Ornithopter.
Repeat.
This clever loop turns the unassuming Ornithopter into a self-sustaining engine by exploiting its free casting cost. When you feed the thopter to Ashnod's Altar, you generate the raw colorless mana you need, while Halvar, God of Battle // Sword of the Realms catches the falling machine to hand and Pitiless Plunderer converts the tragedy into a helpful Treasure token. By spending that Treasure to pay the equipment cost to reattach Sword of the Realms back onto Ornithopter, you break even on your investment and repeat the cycle to generate infinite colorless mana and death triggers.