Zethi and Aphetto Alchemist do not have summoning sickness.
Creatures you control can tap to produce at least ({4} magic symbol) ({W} magic symbol) .
Steps
Declare Zethi as an attacker, triggering its second ability.
Holding priority, activate all mana producing creatures you control by tapping them, adding at least ({4} magic symbol) ({W} magic symbol) .
Activate Lithoform Engine's first ability by paying ({2} magic symbol) and tapping it, copying Zethi's triggered ability.
Resolve the copy of Zethi's ability, creating a copy of each card exiled with a kick counter of it and causing you to pay ({1} magic symbol) ({W} magic symbol) to cast the copy of To Arms!.
Resolve the To Arms! copy, untapping all creatures you control and drawing a card.
Activate Aphetto Alchemist by tapping it, untapping Lithoform Engine.
Repeat from step 2.
Results
Infinite card draw.
Infinite draw triggers.
Near-infinite magecraft triggers.
Near-infinite mana nonland permanents you control can produce.
Near-infinite storm count.
Near-infinite untap of creatures you control.
Near-infinite mana creatures you control can produce.