Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter.
Activate Coretapper by paying ({3} magic symbol) and untapping it, giving it +2/+2 until end of turn.
Repeat from step 1 one additional time.
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 and removing three charge counters from it, causing you to take an extra turn after this one.