Isochron Scepter and The Blackstaff of Waterdeep on the battlefield.
Creatures you control can tap to produce at least ({3} magic symbol) .
({U} magic symbol) available.
Steps
Activate all mana-producing creatures you control by tapping them, adding at least ({3} magic symbol) .
Activate The Blackstaff of Waterdeep by paying ({1} magic symbol) ({U} magic symbol) and tapping it, causing Isochron Scepter to become a 4/4 artifact creature.
Activate Isochron Scepter by paying ({2} magic symbol) and tapping it, casting a copy of To Arms! without paying its mana cost.
Resolve To Arms!, untapping all creatures you control and causing you to draw a card.
Activate all mana-producing creatures you control by tapping them, adding at least ({3} magic symbol) .
Repeat from step 3.
Results
Infinite card draw.
Infinite draw triggers.
Near-infinite magecraft triggers.
Near-infinite mana creatures you control can produce.