(an exercise in world building)
The initial plane is where adventurers were born and have most of their adventures. The fairy plane is parallel to the initial plane. It's were fairies live.
The fairy plane is thought to be above the initial plane. From the fairy plane, reflections of the initial plane are visible and somehow influence the fairy plane.
The lower plane is thought to be below the initial plane. Reflections of the lower place are visible from the initial plane and somehow influence it.
The "reflection" goes perpendicularly from planes and goes in a single direction. There is a reflection going from the initial plane to the fairy plane. There is no reflection going from fairy to initial.
The parallelism between planes breaks where a plane stretches to form a well. The bottom of the well might connect or even overlap an adjacent plane or the bottom of a well stretching from the adjacent plane.
Casting spells is effectively forming a well. A lot of energy is necessary, and most of it is waiting to spring back. A careful spellcaster ensures the well closes slowly and does not bounce back, triggering unwanted consequences.
A non-connecting well has an effect on the plane it distorts. A connecting well has an effect on the two planes it connects. A connecting well is a portal, allowing the passage of elements from one plane to the other.
Spellcasters use non-connecting wells to manipulate the law of physics in their plane. Spellcasters of the initial plane use wells connecting to the lower plane to bring in raw elements from there. Spellcasters also use wells to travel from one plane to the other.
A well distorts the flow of time where it sits, it manifests most commonly as the belief that time in fairyland flows differently, while the transition from there and back, through wells, is the cause.
Master spellcasters use this flow distortion to act at "the right moment", but they need a beacon. Those beacons follow the flow of reflection described above, their signal is visible in the plane they're placed in and in higher planes. The strength of their signal vary.