Time Warp in exile (exiled by Arcane Bombardment).
({3} magic symbol) ({U} magic symbol) each turn available.
Steps
Cast Clockspinning with buyback by paying ({3} magic symbol) ({U} magic symbol) .
Arcane Bombardment triggers, exiling an instant or sorcery at random from your graveyard, and casting a copy of Time Warp without paying its mana cost.
Resolve Time Warp, causing you to take an extra turn after this one.
Resolve Clockspinning, returning Clockspinning to your hand.