The Crooked Wizard traded magic secrets with Old Mombi. She acquired three new recipes, four magical powders, and a selection of herbs. Among these acquisitions was a pepperbox containing the Powder of Life, a substance which brings inanimate objects to life, and Wishing Pills, which are silver pills that grant any wish when swallowed, but only if the swallower is able to count to seventeen by twos. (The Marvelous Land of Oz)
Dr. Nikidik never appears in person in The Marvelous Land of Oz, but he is mentioned as both the Crooked Wizard and Dr. Nikidik. According to The Road to Oz the Powder of Life was made by a Crooked Sorcerer, and in The Patchwork Girl of Oz it is a Crooked Magician named Dr. Pipt. While it is not explicit whether the Crooked Wizard, Crooked Sorcerer, and Crooked Magician are one and the same, most of modern stories consider them to be two distinct individuals who use each other's name. This includes Hugh Pendexter III's Wooglet in Oz, Greg Gick's Bungle and the Magic Lantern of Oz, Philip John Lewin's The Witch Queen of Oz and The Master Crafters of Oz, Edward Einhorn's The Living House of Oz and Richard Capwell's The Red Gorilla of Oz, amongst others. As per these accounts, Dr. Pipt is the creator of the Powder of Life, while Dr. Nikidik is the creator of the wishing pills.
Non-Canon: Dr. Nikidik also makes a small cameo in Gregory Maguire's Wicked: The Life and Times of the Wicked Witch of the West, in which he teaches natural sciences to students in the Gillikin college town of Shiz. At one point he attempts to bring a painting to life with the Powder of Life, but instead brings a rack of antlers to life.