Magistrate's Scepter and Clock of Omens on the battlefield.
You control at least five additional artifacts.
({12} magic symbol) each turn available.
Steps
Activate Magistrate's Scepter's first ability by paying ({4} magic symbol) and tapping it, putting a charge counter on Magistrate's Scepter.
Activate Clock of Omens by tapping two artifacts you control, untapping Magistrate's Scepter.
Repeat two additional times.
Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, causing you to take an extra turn after this one.