How might one work cursed items so that users are affected by them unknowingly?

[Ken L]

I don't think you can automate this. Say they have a cursed sword that reduces will saves. Let them roll normally, but mentally keep track of the penalty to ajudicate pass/fail. If you're using auto pass/save then you're screwed unless you can hide the modifier calculation to only display base roll and success/fail. As for hiding the penalty on the sheet, I have no clue, perhaps a sheet mod only gms can see.

[Mortar]

Doesn't FG have the functionality to leave an item unidentified and handle any modifiers in secret? Pretty sure that is in the Pathfinder/3.5 rules set.

[Minty23185Fresh]

(Nylanfs...)
Exactly! Right?
I have one player, a bit hyper, easily distracted and bammm! Random die roll.
A random fruitless passive perception check gives meaning a player's random flick-of-the-die.
(Facetiousness in not always, completely lost on me...)

[Minty23185Fresh]

I don't think you can automate this. Say they have a cursed sword that reduces will saves. Let them roll normally, but mentally keep track of the penalty to ajudicate pass/fail. If you're using auto pass/save then you're screwed unless you can hide the modifier calculation to only display base roll and success/fail. As for hiding the penalty on the sheet, I have no clue, perhaps a sheet mod only gms can see.

Or a truly "invisible" effect. The effect is only visible to the GM in the combat tracker. AND, applies itself, but does not reveal itself (the details) in the chat window.

For example, a "Coin of Magic Undoing" which when in a character's possession, undoes the effects of any magic item. The player has a +2 longsword and the coin. Rolls a 16. Usually at +2 (=18). The coin modifies this back down to 16. The chat window would state something to the affect of: 16 (+ 2) Miss!

Of course, the astute player might say, "hey wait a minute, that's 18, Maggie hit with a 17, that should be a hit!?!"
To which of course the the DM is going to have to reply, "Hummm... No, it's correct, it's a miss."
Head scratching. Whining. Complaining. Shouting..
"Well.... Maybe you should review your inventory."