Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter.
Activate Magistrate's Scepter's first ability by paying ({4} magic symbol) and tapping it, putting a charge counter on it.
Activate Tezzeret's first loyalty ability by putting a loyalty counter on it, untapping Coretapper and Magistrate's Scepter.
Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter.
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.