Temporal Vault

You spend the casting time constructing an immovable abnormality within spacetime. The point you choose manifests a keyhole matched to the padlock and key provided, which is invisible to all but the caster (excluding spells and abilities that allow creatures to see through invisibility and illusions). The key used in the casting is the only way to access the created space, short of a Wish or equivalent 9th level spell.

You decide on the physical space the vault occupies, ranging from 1 cubic inch to 5 cubic feet. If this space contains any creatures or magical items upon casting, the spell immediately fails. All other contents within this space are displaced until the spell ends. The appearance of the space is decided upon casting, but is restricted to static surfaces as per the Minor Illusion spell. The opening revealed by using the correct key can be of any size, provided it is smaller than the dimensional face it is attached to.

The space created manipulates space or time.

Space. You create an extradimensional space whose internal dimensions vastly exceed the space available locally. The internal space can be 1,000 times greater or smaller than the original dimensions.

Time. The internal dimensions remain the same, but you can slow the passage of time for all objects and creatures within the space. You can choose any reduction of time up to complete stasis (i.e. no time passes within the space until the spell ends).

This space can be dismissed at any time by the caster whilst they are touching the material component key. The spell will also end if a creature able to detect the keyhole succeeds on a Thieves' Tools check equal to your spell save DC + the spell level. When the spell ends, the contents of the extradimensional space are ejected from the point of the keyhole, after the originally displaced objects have been restored. If any creatures or objects are returned to a previously occupied space, it takes 10d10 force damage before being moved to the nearest available space.