In D&D 3.5 fear is a very fun mechanic, typically the province of enemies but also something you can build a character concept around. Rather than describe all the rules here, I'll link to this handbook on how fear works and how best to use it. This specific question is about the capstone ability for fear-based prestige class Dread Witch:
Reﬂective Fear (Su): At 5th level, any fear effect against which you successfully save is immediately targeted back at the source. You still gain the benefits of absorb fear. If the source of the fear effect fails its save, everyone else who might have been subject to the fear effect (such as your companions) immediately gains a second saving throw to shake off the effects, as they observe the object of their fear itself grow terriﬁed.
I love this ability, but there are a lot of cases where it's not clear exactly how it works. If a spell both causes a "fear effect" and does something else - either natively or because a fear effect has been added with Fearful Empowerment (another Dread Witch ability) or the Fell Frighten metamagic, for example - is only the fear portion of the spell reflected, or is the entire spell the "fear effect" and thus reflected? What about AOE: the effect is "targeted" back on its source, so does that mean only the caster is affected or that the spell affects everyone in a normal radius centered on the original caster? Last but not least, are metamagics that were applied to the original ability also reflected, and if so is the caster or the Dread Witch in control of metamagics like Chain Spell (which allows a single-target spell to target multiple nearby creatures, typically of the caster's choice)?