A plot device where a seemingly unsolvable problem is suddenly resolved by an unexpected power or event, often appearing 'from nowhere.'
Deus Ex Machina ('god from the machine') originated in ancient Greek theater, where a crane (the machine) would lower actors playing gods onto the stage to resolve the play's conflicts. In folklore and fairy tales, this appears as sudden divine or magical intervention that saves the hero at the last moment. Examples include the sudden appearance of a fairy godmother to solve Cinderella's problems, magical animals that appear to help the lost protagonist, or divine intervention that saves the hero from certain death. While criticized in modern literature as contrived plotting, this device was perfectly acceptable in pre-modern storytelling, where gods, spirits, or fate were believed to actively intervene in human affairs. In fairy tales specifically, such interventions often reward the hero's prior good behavior (kindness to animals, persistence in trials) rather than being completely arbitrary.
In Propp's morphology, the character who provides the hero with a magical agent or essential knowledge needed to complete their quest.
An enchanted item that assists the protagonist in overcoming obstacles, such as a cloak of invisibility, seven-league boots, or a magical sword.
A magical change in a character's form, such as a prince becoming a beast or a girl transforming into a bird, central to many fairy tales.