Activate Nykthos, Shrine to Nyx's last ability by paying ({2} magic symbol) and tapping it, adding at least ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) .
Activate any other land by tapping it, adding ({1} magic symbol) .
Cast Cloud of Faeries by paying ({1} magic symbol) ({U} magic symbol) .
When Cloud of Faeries enters the battlefield, it and Clement trigger.
Resolve the Clement trigger, choosing to return Shrieking Drake from the battlefield to your hand.
Resolve the Cloud of Faeries trigger, untapping the land(s) from step 1 and 2.
Cast Shrieking Drake by paying ({U} magic symbol) .
When Shrieking Drake enters the battlefield, it and Clement trigger.
Resolve the Shrieking Drake trigger, returning Cloud of Faeries from the battlefield to your hand.
Resolve the Clement trigger, choosing to return nothing.
Repeat.
Notes
If your devotion to blue is at least four, this also produces infinite mana and infinite untap of lands you control.
If you have a creature with mana value 0 that can survive after being cast for 0 mana, you can bounce it each time in step 9 and also cast it infinite times.