Activate Chromatic Orrery's first ability by tapping it, adding ({5} magic symbol) .
Cast Battle Hymn by paying ({2} magic symbol) , adding ({1} magic symbol) for each creature you control.
Cast Quasiduplicate by paying ({3} magic symbol) , creating a token copy of Izzet Chronarch.
The Izzet Chronarch token enters the battlefield, triggering its ability twice, returning Battle Hymn and Quasiduplicate from your graveyard to your hand.
Repeat from step 2.
Once you have infinite mana, you may return any other instant and/or sorcery cards in your graveyard in place of Battle Hymn.
Results
Infinite casts of instants and sorceries in your hand and graveyard.