You control an additional land that can tap to produce ({U} magic symbol) .
Steps
Activate Azorius Chancery and the additional land by tapping them, adding at least ({1} magic symbol) ({U} magic symbol) ({U} 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 two lands from step 1.
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 you control a second land that produces two or more mana, this also produces infinite mana.
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.