The crystal would be kept inside the Tower of Fate, but it could also be summoned by Fate at will and it would travel across the air to reach the summoner.
The Orb of Nabu is a mystical globe of crystal used by Dr. Fate to learn about dangers and the unknown in general.
- Doctor Fate first used a crystal ball to communicate with Inza Cramer in More Fun Comics #59. Fate started using a crystal ball frequently, but the item was not properly given its name until The Flash #305.
Links and References