As a GM, your powers within the games you own is nearly absolute. You can add and remove characters (both PCs and NPCs) as you wish, move them around groups as needed, change their appearance and tags, even go so far as to post as another PC. You can post things that only certain players can see, and even post them in a way that doesn't tell those players the detail is hidden from others.

But one thing you can't do, is roll the dice as another player. If you do, the Die Roller log shows "[GM], on behalf of [PC], rolled X."

I mean, sure, you can go back and delete those rolls, but if all the players have been using the die-roller and you pretend to be one of the PCs in order to deceive them, the die-roller will give you away if the players are paying attention.

Would it be possible to add a check-box to the die roller's settings that suppresses the "on behalf of" part of the log? Maybe have it override the "for the NPC" bit as well?

  Why, would you want to do this? 'on behalf of should be enough 'Private rolls' shield anyone  from  seeing it.

 to want to go out  and Use  an OOC thing like a dice  roller to deceive a player ( or players) seems to be a very...untrustworthy.. thing to do. For players who are looking for an even playing field,

If you're pretending to be a player, the player you're pretending to be should be in the main pulldown.

Not that I approve of doing that, because it seems really odd.

In one of my games, the PCs have run into an impostor. I've been using the ability to post as this PC to sow confusion -- at least until they figure out who's the real one. I was just noticing that the die-roller might be a giveaway if they're paying attention to it.

Now, when I'm actually acting on a PC's behalf (say, if they're away for a while), then I have no problem with the system showing such. But if someone in the game is pretending to be one of the PCs, and they do something that necessitates rolling dice, it looks a little suspicious if it shows the GM is doing the rolls.

well!..that makes a bit more sense. Though I  rather  just withhold OOC info rather  then using OOC to influence that.

but he's saying the imposter is suppose to look like a player.  If he asks for an initiative roll from his group of players, and one player doesn't post at all, it might get noticed.

The solution here, is for RPoL to add a setting to the die roller that lets the GM make ALL rolls secret.

Presumably the real PC knows who's who, it's just the others you need to fool. Blocking ALL die rolls for that character from them would work. They could see their own (and still cut and paste to a post if/as necessary) but no one else's.

or just add players to the options of choices a gm can roll as, that seems simpler.  We can already post as them.

That exists. Click the button to change the roller's default settings, mark the Secret Roll box, and save that. If the game's premise is "one of you is an impostor", then that should have been set on from the beginning. If this is a one off adventure, and especially if the players don't know anything is amiss just yet, then suddenly setting the roller to make all rolls private would be an OOC tip off that there's something to watch out for in the first place. If they've already discovered that someone's an impostor but don't yet know who, then the sudden shift to all secret rolls would work.

Really depends on how this specific situation has been set up beforehand, though. And yeah, if your replaced player is in on it, then just get them to make the rolls themselves and you'll be golden.

So it does. Cool. Thanks, I can use that myself, although for other reasons.

Well... if this is a one off situation, you have the capability to give the player a spare NPC for a moment, move their character to you.  Then make the die roll as them, then move their character back to them, and remove the NPC you gave them.

This is truly being an impostor, but is possible, and as the GM, it is your game, so your prerogative.  But if this is important enough for you, it is doable in that manner.

Just hope the Player doesn't log in during that minute or so...

I believe the system already caters for this.  When you have a PC assigned to yourself it appears in the main list as well as the "on behalf of", obviously allowing you to do both options.

If i understand the situation here is you want to roll as a PC that's assigned to a player and have it coming up as rolled by them.

To be honest I think that's too fringe to change the roller for, unfortunately i can't add options for every possible scenario.

Also consider that rather than possibly alerting other players, if this change is made then you'll definitely alert the player who actually controls the PC.