Activate Dihada's second loyalty ability by removing three loyalty counters from it, causing you to reveal the top four cards of your library and put them into your graveyard, and create eight Treasure tokens.
Activate the Treasures by tapping and sacrificing them, adding 2.
Activate Meticulous Excavation by paying 2, returning Dihada from the battlefield to your hand.
Cast Dihada by paying 1.
Repeat.
This loop hinges on Dihada, Binder of Wills generating an absolute windfall of mana through her minus ability, which dumps cards into your graveyard while dropping a pile of Treasure tokens. Goldspan Dragon turbocharges this economy by doubling the mana output of those Treasures, turning them into an explosive engine that easily covers the costs of the combo. From there, Meticulous Excavation acts as the revolving door, bouncing Dihada back to your hand so you can recast her fresh and repeat the entire sequence indefinitely.