When Peregrine Drake enters the battlefield, it triggers itself twice due to Panharmonicon.
Resolve one Peregrine Drake trigger, untapping five lands.
Activate those lands by tapping them to add at least ({2} magic symbol) ({U} magic symbol) .
Resolve the remaining Peregrine Drake trigger, untapping five lands.
Activate those lands by tapping them to add at least ({2} magic symbol) ({U} magic symbol) .
Cast Shrieking Drake by paying ({U} magic symbol) .
When Shrieking Drake enters the battlefield, it triggers itself twice due to Panharmonicon, returning itself and Peregrine Drake from the battlefield to your hand.
Repeat.
If you can produce at least one additional mana in step 4, this combo produces infinite mana.