God-Eternal Kefnet + Jace, the Mind Sculptor + Temporal Mastery

God-Eternal Kefnet

Jace, the Mind Sculptor

Temporal Mastery

How it works

1. Activate Jace's zero loyalty ability, putting Temporal Mastery on top of your library.
2. Pass the turn.
3. On your next draw step, when you draw Temporal Mastery, reveal it due to Kefnet's ability, making a copy that costs 2 less to cast.
4. Cast the copy for 3, granting you an extra turn.