The phrase "mystical realm" refers to a magical or spiritual world that is not easily understood or explained. It is a place where supernatural or otherworldly things happen and often includes mystical creatures or mysterious powers. Full definition
This origin story introduces the magical and mystical realms of the Marvel Cinematic Universe.» (bloody-disgusting.com)
Their fight for the love of the Princess triggers a series of adventures for the young Abu that brings him halfway around the world and into mystical realms with help from a towering genie (Rex Ingram), brushing up against the gods and transforming the little thief into a hero in the process. (rottentomatoes.com)
Shadowlands is a dark, mystical realm where the laws of physics are changed, and everything you ever believed in, breaks and inverts. (metacritic.com)