Activate Troubled Healer by sacrificing Orzhov Basilica.
When Orzhov Basilica dies, Toph, Hardheaded Teach triggers, returning Orzhov Basilica from your graveyard to the battlefield tapped.
When Orzhov Basilica 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 Troubled Healer ability
Repeat.
This clever loop transforms a humble zero-mana artifact into a recurring engine by leveraging Toph, the First Metalbender, which turns all your nontoken artifacts into lands. With Orzhov Basilica on the battlefield to bounce your newly minted land-artifact back to your hand upon entering, you can continuously cast it to trigger Toph, Hardheaded Teacher. Finally, Troubled Healer provides the sacrifice outlet needed to send the Basilica straight to the graveyard, where Toph, Hardheaded Teacher’s earthbend safety net instantly returns it to the battlefield to restart the cycle.