Magistrate's Scepter has at least one charge counter on it.
({6} magic symbol) each odd-numbered turn, with ({4} magic symbol) available each even-numbered turn available.
Steps
Activate Karn's Bastion's second ability by paying ({4} magic symbol) and tapping it.
Holding priority, activate Lithoform Engine's first ability by paying ({2} magic symbol) and tapping it, copying Karn's Bastion's ability.
Resolve both Karn's Bastion abilities, putting four 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.
Move to your next turn.
Activate Karn's Bastion's second ability by paying ({4} magic symbol) and tapping it, putting two charge counters on Magistrate's Scepter.