Wishcraft is a stage of witchcraft children enter when they are young. Whenever they wish for someone they really love to be with them, they get their wish.
Tabatha went through this stage when she was two years old, earlier than most witches and warlocks usually do. She first used this power to wish her father to be with her. This caused problems when Darrin's parents, Phyllis and Frank, arrived for a visit. After Adam displayed his first powers, he wished Samantha into the kitchen to be with him.
Witches and warlocks can also wish for things as well as people. Tabatha wished Prince Charming out of a storybook. Because he was a product of wishcraft, he had no substance. He could walk through solid objects like doors. He was also invisible on camera, which caused problems for a McMann & Tate client.
Darrin acquired magical powers when Serena went back in time to give his ancestor, Darrin the Bold, a potion to turn him into a warlock. In the present, Darrin wished for a beer and got his wish. Samantha explained to him that as he gets used to his powers, all of his involuntary witchcraft will go away. His condition was short-lived, however, when Samantha went back in time to reverse the spell.