Activate Bloodflow Connoisseur by sacrificing Dimir Aqueduct.
When Dimir Aqueduct dies, Toph, Hardheaded Teach triggers, returning Dimir Aqueduct from your graveyard to the battlefield tapped.
When Dimir Aqueduct enters, it triggers, returning the artifact cast in step 1 from the battlefield to your hand, as it's a land due to Toph, the First Metalbender.
Resolve the Bloodflow Connoisseur ability
Repeat.
This clever loop turns the laws of reality—and your own artifacts—upside down by exploiting Toph, the First Metalbender's static ability, which turns all your nontoken artifacts into lands. With that foundation laid, casting a zero-mana artifact triggers Toph, Hardheaded Teacher to animate Dimir Aqueduct, setting it up to be sacrificed to Bloodflow Connoisseur. Because Dimir Aqueduct is technically a land thanks to the First Metalbender, its own enters-the-battlefield trigger bounces the zero-mana artifact right back to your hand, while its death triggers are safely mitigated by the built-in safety net of earthbending. By repeating this cycle endlessly, you feed the Connoisseur an infinite stream of sacrifices while generating boundless landfall, enter-the-battlefield, and death triggers to overwhelm your opponents.