Riku of Two Reflections | Dockside Extortionist | Eternal Witness

(and one other card)

Cast
Dockside Extortionist for ({1} magic symbol) ({R} magic symbol) .
When
Dockside Extortionist enters the battlefield, its own ETB triggers and
Riku of Two Reflections triggers.
Stack the triggers such that
Dockside Extortionist's trigger resolves first, creating 5 Treasure tokens.
Pay for the
Riku of Two Reflections trigger using 2 Treasures, creating a token copy of
Dockside Extortionist that creates another 5 Treasure tokens.
Cast
Snap using two of your 8 Treasures, returning
Dockside Extortionist to your hand and untapping two lands, leaving you with 6 Treasure tokens and two untapped lands.
Cast
Eternal Witness with an untapped land and two Treasure tokens, leaving an untapped land and four Treasure tokens.
When it enters the battlefield,
Eternal Witness and
Riku of Two Reflections trigger.
Stack the triggers such that
Eternal Witness resolves first, returning
Snap to your hand.
Before the
Riku trigger resolves, cast
Snap using an untapped land and a Treasure, returning
Dockside Extortionist to your hand and leaving you with 2 untapped lands and 3 Treasure tokens.
Pay for the
Riku of Two Reflectons trigger with 2 Treasure tokens, creating a token copy of
Eternal Witness that returns
Snap to your hand on ETB.
You are now back where you started, but with an extra Treasure token, an
Eternal Witness token, and a
Dockside Extortionist token, and with 2 untapped lands instead of ({1} magic symbol) ({R} magic symbol) .
Repeat for infinite Treasure tokens and creature tokens.