Another question about the Misfortune revelation

[*Khan*]

Can you use this revelation on your friends to reroll a failed attack or save and thereby give them a better “fortune”?

[Fuzzy-Wuzzy]

Not once you know it's failed. You could do it in response to a low roll before the result is revealed, once per day per ally. The revelation name and effect aren't the greatest match.

[Syries]

Correct. If an ally is within 30 feet, you can reroll a low result, but it does have to be before the result is revealed- once you know it’s a failed save you can’t use your misfortune ability.

[Cavall]

Apologies. Deleted my post realized we are talking revelation. I played my witch far too long.

[*Khan*]

(Sorry made an edit) That could make some trouble for the GM to wait awaile after each roll of both players and monsters to see if the player is using this ability...
How do you handle that?
And you need to make all Rolls in the open as a GM.

[Derklord]

Yes - you see the number on the dice (or the GM tells you), and before the GM says whether it's a success or not, you can use the ability. That even works if you know what the result will be (say a natural 20 on an attack roll).