Activate up to two lands by tapping them, adding at least {1}{U}.
Cast Cloud of Faeries by paying {1}{U}.
Archmage of Echoes triggers, copying Cloud of Faeries.
Resolve the copy of the Cloud of Faeries spell, creating a token copy of it.
When the Cloud of Faeries token enters the battlefield, it triggers, untapping up to two lands.
Activate up to two lands by tapping them, adding at least {1}{U}.
Resolve the original Cloud of Faeries spell.
When Cloud of Faeries enters the battlefield, it triggers, untapping up to two lands.
Cast either Quickling or Faerie Impostor from your hand by paying its mana cost.
Archmage of Echoes triggers, copying the Quickling or Faerie Impostor spell.
Resolve the copy of the Quickling or Faerie Impostor spell, creating a token copy of it.
When the Quickling or Faerie Impostor token enters the battlefield, it triggers, returning Quickling or Faerie Impostor from the battlefield to your hand.
Resolve the original Quickling or Faerie Impostor spell.
When Quickling or Faerie Impostor enters the battlefield, it triggers, returning Cloud of Faeries from the battlefield to your hand.
Repeat.

Infinite creature LTB

Infinite creature ETB

Infinite storm count

Infinite creature tokens

Infinite mana lands you control can produce

Infinite untap of lands you control

Archmage of Echoes

Quickling

Cloud of Faeries

Faerie Impostor

Activate up to two lands by tapping them, adding at least {1}{U}.
Cast Cloud of Faeries by paying {1}{U}.
Reflections of Littjara triggers, copying Cloud of Faeries.
Resolve the copy of the Cloud of Faeries spell, creating a token copy of it.
When the Cloud of Faeries token enters the battlefield, it triggers, untapping up to two lands.
Activate up to two lands by tapping them, adding at least {1}{U}.
Resolve the original Cloud of Faeries spell.
When Cloud of Faeries enters the battlefield, it triggers, untapping up to two lands.
Cast either Quickling or Faerie Impostor from your hand by paying its mana cost.
Reflections of Littjara triggers, copying the Quickling or Faerie Impostor spell.
Resolve the copy of the Quickling or Faerie Impostor spell, creating a token copy of it.
When the Quickling or Faerie Impostor token enters the battlefield, it triggers, returning Quickling or Faerie Impostor from the battlefield to your hand.
Resolve the original Quickling or Faerie Impostor spell.
When Quickling or Faerie Impostor enters the battlefield, it triggers, returning Cloud of Faeries from the battlefield to your hand.
Repeat.

Reflections of Littjara

Activate any number of creatures you control by tapping them, adding at least {1}{G}{U}.
Cast Quickling by paying {1}{U}.
When Quickling enters the battlefield, it, Clement and Intruder Alarm trigger.
Resolve the Intruder Alarm trigger, untapping all creatures.
Holding priority, activate any number of creatures you control by tapping them, adding at least {1}{G}{U}.
Resolve the Clement trigger, returning nothing to your hand.
Resolve the Quickling trigger, returning Clement from the battlefield to your hand.
Cast Clement by paying {1}{G}{U}.
When Clement enters the battlefield, it and Intruder Alarm trigger.
Resolve the Clement trigger, returning Quickling from the battlefield to your hand.
Resolve the Intruder Alarm trigger, untapping all creatures.
Repeat.

Infinite mana creatures you control can produce

Infinite untap of creatures

Clement, the Worrywort

Intruder Alarm

Cast Nethroi either from your hand or from the command zone for its mutate cost by paying {4}{G/W}{B}{B}, putting it under a non-Human creature you control.
Nethroi triggers, returning Quickling and Mitotic Slime from your graveyard to the battlefield.
When Quickling enters, it triggers, returning Nethroi from the battlefield to your hand.
Activate Phyrexian Altar twice by sacrificing Quickling and Mitotic Slime, adding {B}{B}.
When Mitotic Slime dies, it triggers, creating two 2/2 Ooze creature tokens.
Activate Phyrexian Altar twice by sacrificing the Oozes, adding {1}{G/W}.
When the Oozes die, they trigger, creating four 1/1 Ooze creature tokens.
Activate Phyrexian Altar three times by sacrificing three Oozes, adding {3}.
Repeat.

Combos with "Quickling"