Arcane Bombardment + Inspiring Refrain + Jhoira's Timebug + Time Stretch

Arcane Bombardment

Inspiring Refrain

Jhoira's Timebug

Time Stretch

How it works

1. Cast Inspiring Refrain by paying 4.
2. Arcane Bombardment triggers, exiling a random instant or sorcery from your graveyard, and then casting a copy of Time Stretch without paying its mana cost.
3. Resolve the Time Stretch copy, causing you to take two extra turns after this one.
4. Resolve Inspiring Refrain, causing you to draw two cards and exile Inspiring Refrain with three time counters on it.
5. Activate Jhoira's Timebug by tapping it, removing a time counter from Inspiring Refrain.
6. Move to your first extra turn, removing a time counter from Inspiring Refrain during your upkeep.
7. Move to your second extra turn, removing a time counter from Inspiring Refrain during your upkeep.
8. Inspiring Refrain triggers, causing you to cast it from exile without paying its mana cost.
9. Repeat from step 2.