The Actualization skill represents your characters' ability to manifest alternate realities. Certain individuals are more naturally gifted at actualization, and, in general, actualization comes more naturally to children than adults.
As Actualization is necessary to manifest a Diver, NIAN typically selects individuals with some talent at Actualization to become Mindwalkers.
The ideas behind Actualization are similar to the ideas for Declaring a Story Detail. However, Actualization is more meant for things a character can believe in the present, and things that a character can change in the mental world. As with declaring a detail, Actualization has lasting consequences - once a character believes something, they continue believing it, even outside of the current scenario.
A major difference between declaring a story detail and using Actualization is that Declaring details requires the expenditure of a Fate Point, while Actualizing something requires a roll. Because of this, attempts to Actualize something can have various rates of success.
Overcome: Actualization allows you to overcome any obstacle that requires a belief in an alternate reality, or a reality that exists outside of the assumed rules.
Eg1: "Scissors cuts paper, but gun shoots scissors".
Think about it as if you are playing a game with a five-year-old. If they are cornered, what ways would they use to get out?
Create an Advantage: When you're creating an advantage with Actualization, you're manifesting something or changing the nature of something so that it becomes useful to you.
Attack: Actualization is not often used in conflict, but here is one possibility: Against a foe who is afraid of snakes, a character could actualize "From out of the tree trunk crawls a giant snake, who was awoken by the sound of our battle." If they were successful, the foe might take mental stress.
Defend: Actualization is not often used to defend - the most common way to defend against Actualization is via Logic. Actualization can be used to contest other Actualizations in the case that two Divers create paradoxes, (A "sharpest spear" vs "ultimate shield" scenario - in this case, the Diver with the higher Actualization would win.)