Dimensional Borrowing

Using Potter's 9¾th Law of the Conservation of Quantum Dimensional Physics, a spellcaster is able to perform functions in a universe consisting of a different number of dimensions by "borrowing" a dimension temporarily from a higher one. The key caveat of note is the word "temporary". Dimensional Borrowing is subject to the rigid and unyielding laws of Multiverse Standard Time(MVST) and cannot be sustainable.

Effect

The spellcaster is able to create a temporary miniverse in which beings from different dimensions or universes may interact. Because this is a kind of "in-between" space, the caster has some ability to control the physical dimensions and physical laws, usually "easing" between them as a gradient rather than as a cliff-like discontinuity.

Side/Secondary Effects

Even with the ability to mitigate spatial dimensions and physical or magical laws, the experience can still be disorienting and even traumatic in the hands of less skilled magic-users.
Also, one must be aware that these temporary spaces are subject to Multiverse Standard Time. If a miniverse created using Dimensional Borrowing runs out of time, it can collapse. If the difference between universes and dimensions is great, this can be a very sudden and violent collapse and cause many kinds of trauma to those still inside.