Activate Jace's zero loyalty ability, putting Capture of Jingzhou on top of your library.
Move to your next turn.
On your next draw step, when you draw Capture of Jingzhou, reveal it due to Kefnet's ability, making a copy that costs ({2} magic symbol) less to cast.
Cast the copy for ({1} magic symbol) ({U} magic symbol) ({U} magic symbol) , granting you an extra turn.