Dice don't lie, but players might.
Most groups have someone who gets these dice rolls that seem to defy the law of averages. They always seem to pull off a critical hit or two during a fight. Or they never seem to be hindered by the spell that seems to incapacitate half the party because they managed to pull off the resistance roll even though they had the least chance.
So how do you deal with this sort of thing?
There is a lot of advice out there on this topic. Before you go and pick a solution that someone else wrote down, even me, give some thought to how it's effecting your game.
Is this player killing the fun because they seem to be a super hero compared to the rest of the heroes? Is it ruining your plot because they aren't paralyzed and therefore easily captured like everyone else? Figure out how it's effecting the game. Talk to the other players about it. If it bothers them, then as the GM you need to take some sort of action.
What sort of action you take could be anything from expelling the cheating cheater face from the game, to having a heart to heart talk with them about how their cheating is only hurting them. Or, you could just operate on the assumption that this is going to happen, and make sure they need to roll for things less.
We likes the dice we do.
Some games don't really have a dice mechanic. This article is really about engines that have a dice mechanic for task/conflict resolution. But this sort of behavior might also creep into systems that are free of dice, so stick around and maybe you'll pick up something that might help you with some other issue.
Back to the dice thing. Don't ask them to roll for things. Obviously there will be times when this is necessary, but you want to minimize it if you can. Compile a list of everyone's skills (skills is where you will have the most discretion over when to roll) so you can see what everyone is good at. Then make sure you engineer encounters so that everyone but your cheater gets to roll dice. There will be times you just can't pull it off, but you can make it work for you fairly often.
Then, you make sure that whenever possible, you make rolls for the cheater. Stealth check, you roll it. Appraise check, you roll it. You do this for everyone so your cheater doesn't feel singled out, but you take control of the dice when you can to minimize the chance that the cheater can cheat.
Another tactic you can use is to reward failed rolls. Perhaps every time someone fails a roll they get a poker chip. These can be cashed in for bonuses to later rolls. Perhaps only damage rolls, or skill checks. You can also reward failure with story. Maybe the failed diplomacy check makes someone else take note of you and approach the PC later to offer a job, or an alternate way to do the thing you were trying to use diplomacy to use earlier. Showing that failure is okay can reduce the incentive to cheat.
Does any of it really matter.
You may find that no one really cares about the cheater. If everyone is having a blast in the game and they think it's fun, they may be fine with the cheater cheating. It may be how they have fun. I know, that doesn't seem right, but it might just be how they get their fun. Most of the time we play these games to exercise a bit of control over the world that we don't have in real life. So maybe, just maybe, the cheater is exercising control by cheating the dice. In the end, it boils down to weather or not we're all having a good time.
If your stories are good, and your NPCs compelling, and your players are there and having fun at game sessions, it might be okay to let things like cheating some dice rolls slide.
Do you have a preferred tactic for dealing with someone who maybe has trouble reading the right number off their dice? Share with us in the comments below.