Can't comment on the source material except to point out that you should judge the Power based on what it does in DFRPG, not by what it does in the source material.
As I don't entirely agree with the power as written, allow me to quote a player of mine: "I refute your reality and substitute my own!"
Note: It's been a long day, but I wanted to get this written out before I forgot to do so. And this is just a draft of ideas, so pick apart as you choose.
Reality Marble [-2, plus powers from "Unlocked Potential"]
Description: A reality marble is placing your own inner world materialized and projected onto reality. You have the ability to project a limited world of your design into reality.
Skills Affected: Conviction, others.
Effects:
Personal Battleground: The created location appears as you choose, it defines your nature, and can take any form. This form cannot change after creation. Additionally, create a pair of Location Aspects that are always in place. (Some canon examples are "Field of Swords," "Overwhelming Forces," "Memory Suppression," and "Desert Wasteland"). These aspects are important for "Projection," below. These scene aspects cannot be removed, and new scene aspects cannot be created within the Reality Marble.
Projection: As an action, spend a Fate Point and roll your Conviction vs. the highest Discipline of your targets (can name multiple targets within the same zone). If you succeed, you are given a number of free tags to any of your Scene Aspects equal to the margin of success, and only you can access the Aspects. If you tie, you are only given one free tag, but only you can access the Aspects. If you fail, you must spend Fate Points to access your Scene Aspects, and ALL within the Marble may access the Aspects. Regardless of success, all targets are brought within the Marble, and are removed from any current conflict that was not with you.
Trapped: All who enter the Reality Marble are trapped until the Marble is broken, you are Taken Out, or an amount of time equal to your margin of success after "half of minute" on the time table has passed. Extra amount of time can be acquired by taking a Mental Stress for each additional turn. If you choose to end the effect of the power, you may place your victims at any location up to a zone away.
A Reality Marble can be destroyed by a powerful attack targeting it. The Reality Marble automatically has a defense skill of your Conviction + your Margin of Success on the Conviction roll. When the Marble is destroyed or you are Taken Out, everyone returns to where they were when this power activated.
Unlocked PotentialAs the Reality Marble follows the rules governed by the creator, the creator often has an ability that is inaccessible to them in the "real world." While within the Reality Marble, you are able to use that special ability.
Purchase a single or multiple powers with +1 point refund due to the limitation of being accessible within the Marble.
And that's what I have offhand. Too tired to tweak it any further tonight; will look at responses later.