Crystal balls are standard equipment among practitioners of magic. They're portable tools that can be used at all times to see other places and the events playing out there. Such a vision can be a delayed presentation and so it is up to the user to understand what their magicl ability in combination with the qualities of their particular crystal ball is worth to accurately utilize the feedback.
History
Crystal balls are orbs of either cut out from large rocks of crystal or formed from glass. Their size and weight makes them fit to just be carried in one hand. Crystal balls are common tools of magic that grant visual and sometimes audial feedback to their users. Depending on the magical skill of the user and the quality of the ball, they can display events from anywhere on the planet and possibly even across dimensions. "Campaign Carnage, Part 1" One possible consequence of using an older ball is that the feedback might be delayed and not up to date with current events. "Dangerous Currency, Part 1" The mystic community also uses crystal balls to stay in touch with one another, maintaining an internet-like network accessible through the tool. "F.O.W.L. Disposition, Part 2"
Fiction
Boom! Studios comics
At their hideout in an abandoned part of the St. Canard Subway, Negaduck and Magica De Spell watch Darkwing Duck and his team have their victory over Taurus Bulba by means of Magica's crystal ball. "The Duck Knight Returns, Part 4" They've got their own plot going: abduct and brainwash Darkwings from different dimensions and set them loose against Darkwing Duck. They've turned their part of the subway into a dimensional gate for this purpose. After fetching another Darkwing, they get to work on more technical preparations, Negaduck using a computer and Magica her crystal ball. Once they release the first few Darkwings, they keep tracks of their actions with the crystal ball. "Crisis on Infinite Darkwings, Part 1"
Morgana Macawber is asked to babysit for Gosalyn, much to their mutual annoyance. With Gosalyn in her room, Morgana gets out her crystal ball gets on the network. She finds that the entire mystical community is buzzing about a cataclysmic event that is to occur that very night. With Darkwing nowhere to be found, she makes her way to the Quackwerks building; to Launchpad's office. She hands him her crystal ball and together they read another message about a vision of a "purple pawn" and of a possible relation to the rise of Duckthulhu. Morgana explains who Duckthulhu is and together they start an investigation as to what is going on. "F.O.W.L. Disposition, Part 2" With Morgana lost during the fight with Duckthulhu, Launchpad takes Darkwing to various mystics in hopes that one of them can sense Morgana's fate or whereabouts. One mystic, Madame Kira, searches for answers in her crystal ball, but she gets sidetracked by a honkball game she sees instead. The two crimefighters leave in worse spirits than they came in. "Campaign Carnage, Part 1" Some time later, a teamup of the Phantom Blot, the League of Eve-il, the Fearsome Four, and the Beagle Boys converts the entire city of St. Canard into their personal playground by means of the ink. Morgana keeps tracks of proceedings in the city with her crystal ball out of habit, but finds videoscreen feedback from the city itself a much more efficient source of information. "Dangerous Currency, Part 1"
Joe Books comics
At their hideout in an abandoned part of the St. Canard Subway, Negaduck and Magica De Spell watch Darkwing Duck and his team have their victory over Taurus Bulba by means of Magica's crystal ball. "The Duck Knight Returns, Part 4" They've got their own plot going: abduct and brainwash Darkwings from different dimensions and set them loose against Darkwing Duck. They've turned their part of the subway into a dimensional gate for this purpose. After fetching another Darkwing, they get to work on more technical preparations, Negaduck using a computer and Magica her crystal ball. Once they release the first few Darkwings, they keep tracks of their actions with the crystal ball. "Crisis on Infinite Darkwings, Part 1" "F.O.W.L. Disposition, Part 2" "Campaign Carnage, Part 1"