Theoretical situation: A Hunter figure is adjacent to two hostile figures, that are also adjacent to each other. One of the figures activates and wants to move away from the Hunter, and to do that they decide to move through the other figure adjacent to them (which is also adjacent to the Hunter). When they move into the space of the adjacent figure, they are also entering a space adjacent to a Hunter, so the Hunter figure plays Dirty Trick: "Use when a hostile figure enters an adjacent space. That figure must choose to either suffer 3 strain or become Stunned."

So what happens if the figure moving decides to become stunned? Does it move out of the space it's in before applying the effects of Dirty Trick? Can it not choose to become stunned because that would create a rules paradox that would cause the game to explode? Does it become stunned while occupying another figure's space and because it can no longer voluntarily exit that space but can't end it's movement there does the game forcefully eject the stunned figure into an adjacent space without using any movement points? Can the Hunter player not use Dirty Trick while the enemy figure is moving through an occupied space, but then its next move is into a non-adjacent space to the Hunter so it loses its opportunity to use Dirty Trick?

Additionally, what happens if the Hunter wants to play Parting Blow after Dirty Trick when the adjacent figure tries to exit the other figure's space?

If there is no prerequisite listed, the figure can choose to become stunned. In that case handle the case as-if the figure had lost movement points while moving - i.e. the figure gets pushed to the closest valid space (controller of the figure breaks ties). (I'm pretty sure this has been ruled before. Perhaps it was for the campaign mission Incoming.)

During this you can play Parting Blow, because it doesn't care whether the figure exits a space voluntarily or not.

After that, if the stunned figure has an action remaining, it can choose to remove stunned and continue spending movement points before ending its activation. Or do something else completely.