Each Realm is basically a condensation of the essence they encapsulate, but the Realm of Reflection is possibly one of the most interesting options.
As soon as you arrive, going through the onyx door in the Ideal Gate, you see.. a barren wasteland. Worse yet, you see a plain of nothingness. Here, in all Realms, the sky is gray, but a few shades lighter than the soil, so it is a horrible duotone of straightened horizon. You may walk, it won't change.
That is, until you interact with the first rock. If you are trying to find something in this barren place, you will feel the full momentum of your walking hitting you back, along with pinkish shockwaves rippling across the rock's outer surface. Rippling like waves in a lake, losing saturation and thickness until the rock is invisible again. Or better yet, non-existent.
You see, that is the difference between being suddenly visible and being suddenly present. If you shoot an arrow, or any projectile across this realm, it will hit NOTHING. For it has no intention of interacting, or touching anything. A being, however, can apply intention here and will receive a REACTION back. That's why you trip on rocks, but not arrows.