At the beginning of your upkeep, Palace Siege triggers, returning Coretapper from your graveyard to your hand.
Cast Coretapper by paying ({2} magic symbol) .
Activate Coretapper's first ability by tapping it, putting a charge counter on Magistrate's Scepter.
Activate Coretapper's second ability by sacrificing it, putting two charge counters 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.