Airway Spire

If Airway Spire would enter the battlefield, tap two untapped Airships you control instead. If you do, put Airway Spire onto the battlefield. If you don't, put it into its owner's graveyard.
{t}: Add one mana of any color to your mana pool.
{t}: Add two mana of any one color to your mana pool. Spend this mana only to cast Airship spells or activate abilities of Airships.