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 goes through this stage when she is two years old, earlier than most witches and warlocks usually do. She first uses this power to wish her father to be with her. This causes problems when Darrin's parents, Phyllis and Frank, come to visit. After Adam displays his first powers, he wishes Samantha into the kitchen to be with him.
Witches and warlocks can also wish for things as well as people. Tabatha wishes Prince Charming out of a storybook. Because he is a product of wishcraft, he has no substance. He can walk through solid objects like doors. He is also invisible on camera, which causes problems for a McMann & Tate client.
Darrin acquires magical powers when Serena goes back in time to give his ancestor, Darrin the Bold, a potion to turn him into a warlock. In the present, Darrin wishes for a beer and gets his wish. Samantha explains to him that as he gets used to his powers, all of his involuntary witchcraft will go away. His condition is short-lived, however, when Samantha goes back in time to reverse the spell.