Vogler, Memo From the Story Department:
The hero is tested and sorts out allegiances in the Special World.
Once the hero enters the extraordinary world, he or she will make friends and enemies, encounter various trials and challenges, and begin to learn the rules of this new and unfamiliar place. This is a key time for character development because we get to see how the hero and his or her companions react under the stresses of being in a new and different place. This series of tests and complications are what form the bulk of Act 2, culminating in the midpoint, where the protagonist learns or finds out something important, pushing them from a reactive state to a proactive state.
Batty - Movies That Move Us:
Physically, the protagonist undertakes the course of the journey. His path is laden with physical tests, obstacles and the meeting of new people, all of which become progressively difficult as the journey goes on. The Special World has a different look and feel to the Ordinary World, with different spaces, faces and rules. There are also different priorities in this world, for the protagonist and its inhabitants. The physical environment is therefore very alien, yet the protagonist does gradually become accustomed to it.
As the physical journey progresses, the protagonist literally or metaphorically faces danger; physical tests and obstacles become so difficult that he comes head-to-head with dark, enemy forces. Nevertheless, he must remember that the physical tools provided by the Mentor will help him in some way.
Vogler, Memo From the Story Department:
Now in a deeper place the hero learns the ropes of an inner Special World, Experimenting with New Conditions, testing his powers and learning who are his inner Allies and Enemies.
Palmer - http://www.crackingyarns.com.au/2011/04/04/a-new-character-driven-heros-journey-2/
Step 6: Disoriented (Tests, Allies & Enemies)
This step of the Hero’s Journey is quite a mouthful, but it’s one of the simpler stages to understand. Remember how scary that first day at school was for you when you were 5 or 6? In this first sequence of Act 2, your hero is similarly disoriented.
In their Ordinary World, the hero might have been “incomplete”, and they might not have been entirely happy, but at least everything was familiar. Now, as soon as they begin to pursue their goal or fix their problem, their world is turned upside down.
The hero can be forced to deal with changes in terrain, as Bertie is in The King’s Speech when he’s forced to leave the familiarity and safety of his palace and come to Logue’s unusual professional rooms.
The protagonist will often have to go through a change of appearance, as Zack does when he gets his locks shorn in An Officer and a Gentleman.