Say a fighter and a witch are trying to find a missing guard. They are talking to a witness that feels a bit fishy to them. The fighter asks the witness a key question. The witch hexes the witness with misfortune in the hopes of making him fumble his possible bluff roll.
A. Does this work?
B. Would the witness be aware of their sudden magically induced bad luck?
I'd say the person would notice. Whether he would know or suspect why it happened is something else.
Succeeding on a Saving Throw: A creature that successfully saves against a spell that has no obvious physical effects feels a hostile force or a tingle, but cannot deduce the exact nature of the attack. Likewise, if a creature's saving throw succeeds against a targeted spell, you sense that the spell has failed. You do not sense when creatures succeed on saves against effect and area spells.
Note: this refers to spells. There is no guide for supernatural abilities.
A) It works if the lie he attempts to tell is short and sweet. If his lie takes more than 6 seconds to complete, then he's no longer under the effects of Misfortune by the time people decide whether or not he's believable, and it has no effect (unless the witch cackles, but that would be flagrantly obvious.)
B) No, I don't think the witness would be aware if they fail their save. If they succeed on their save, they feel the "hostile tingle" and would know something is going on.
That's a good point on the time limit, I didn't think of that. I went ahead and let it work, the witness failed his save but managed to bluff anyway. I was mostly concerned with the witness (an important person) figuring out he was being manipulated or realizing he was under suspicion. I'll assume that since he failed the save he didn't notice. Thanks for helping me parse it out everyone. The successful resist alerting the victim is a good rule to know going forward as well.