The Mirror Dimension is a parallel dimension that allows the user to practice their magical abilities and fight their enemies without the public's knowledge. It is known for rapidly distorting space and landscape, which sorcerers that visit it can control to an extent. Those who use the power of the Dark Dimension have a stronger control over the Mirror Dimension, to the point of being able to fold and warp space in the physical dimension.
The Mirror Dimension allows an advanced sorcerer to train more advanced and dangerous spells without adversely affecting the real world, keep an eye on threats without being noticed, and a prison for those without a Sling Ring. The final usage is paramount that a prisoner is locked without a Sling Ring as it is the only means to escape. However, the realm is shown to be accessible without the use of the Sling Ring, which allowed the likes of the Ancient One and Doctor Strange to transport themselves and others into the dimension, though a Sling Ring was ultimately required to leave it.
