Globe of Invulnerability:
You may cast the following spell once per scenario. An immobile, faintly shimmering magical sphere surrounds you and as many as three others, excluding any magical spells or effects that do not cost at least one fate point to cast. So, for example magic that affects one or more zones in any exchange must make special exception for those sheltered within the Globe of Invulnerability, including the Anti-Magic Field spell. The globe may be dismissed by a hostile mage, as per the rules in the Magic & Damage section but it will automatically cost a Fate point to attempt this. Additionally, the globe carries the aspect Fading Fast.
The material component is a small, spherical gem of some value that shatters upon the spell’s expiration.
You have just read a conversion of the classic Lesser Globe of Invulnerability spell from the freely available Dungeons & Dragons System Reference Document. This is a stock spell that would have been a go-to for any forward thinking mage with a copy of the Player’s Handbook. However like many of D&D’s classic spells, the finer details necessitate the use of special rules. The key feature of this spell is it’s ability to preclude the effects of low-level spells on the area contained within the globe. Specifically the spells precluded are 4th level and lower.
Now, since the rules of FotFR (and probably most Fate games of this ilk, including the Freeport Companion), don’t feature exhaustive spell lists segmented according to level we have to rework the key features of this spell. We do want to capture the spirit of the original spell so let’s consider the intent behind the magic – the globe excludes the effects of all magics of limited potency. In order to replicate this approach we can decide that in FotFR these low-level magical effects will be considered to be any that do not cost at least one fate point to invoke.
Similarly, many spells in the Player’s Handbook specify a duration that is tied to the caster’s level. There being no equivalent to this mechanic in Fate we simply attach an aspect to the spell’s effect – Fading Fast. An experienced mage will likely have a big pool of fate points to draw from, enabling him to keep the spell ‘up’ for longer.
The key thing to bear in mind here is that there is no need to be too technical. Like the example above, if there is a vulnerability inherent to the spell such as a time limit then the simplest way to represent this is with an aspect. The players may need to create an advantage to learn of this aspect although as DM you could rule that any PC mage with some schooling in the Art will be aware of this aspect anyway.
In Fate of the Forgotten Realms each signature spell is accessed through a stunt describing a particular brand of mage. These stunts are known as Mage Archetypes. Like the branching effects detailed in the Skills & Stunts section of the Fate core system, each stunt will branch into a series of signature spells (often hand-picked by the player), reflecting the theme of the archetype. There are many examples in the ‘Dungeon Master’s Guide’ accessible on this site but players and DMs are encouraged to create their own Archetypes, possibly reassigning signature spells from this site or incorporating new spells. Owing to the protective nature of the Globe of Invulnerability it would seem that the Guardian stunt would be a natural home for this spell.