what penalties would you assess?

[morkendi]

In upcoming campaign, bad guy will be using mirrors to enter an extra dementional kind of place. The characters will end up going in as well. The idea is their conscious mind will go into the mirrior immage. The thing is everything on there mirror immage is opposite. Sword is now in left side instead of right. So the bodies muscle memory will be opposite of what the mind is used to. I am thinking just a 10% chance to fail any action, thus not to drastic. They will occasionally fail, but still able to do what they want most the time.

[TheIronGolem]

I don't think a penalty here is necessary or fun - or even "realistic" given that their brains will also be mirrored. That said, if you're going to do one:

1) Just assess a -2 penalty to d20 rolls; adding a second roll will just slow things down unnecessarily. Maybe tack on 10% to ASF too, so that it's not just the martials getting screwed with.
2) Give them a way to mitigate or eliminate the penalty by taking some time to intentionally realign themselves. For example, spend a move action to ignore the penalty for a few rounds, this representing the mental effort you've made to adjust to the mirror effect.
3) Anybody with Two-Weapon Fighting (or any other ability that implies ambidexterity) should probably not have the penalty to begin with.

[IZ42]

I don't think there should really be any sort of penalty attached. Ignoring real life for a moment (where most warriors were trained nearly exclusively to use their main weapon with their right hand, which is silly), and half-way competent adventurer would have trained using both hands. And even if they did train exclusively with their right hand, they still should be able to switch hands just fine, because muscle memory isn't exclusive to just one side.

And ASF chance is generally due to prohibited motion through armor or similar things, not being flip-flopped. Most gestures are easy to perform with either hand, or use both hands.

Also, TheIronGolem, I agree with your statement, but your reasoning is kinda silly. The whole 'left-brained/right-brained' thing is actually false, there is no difference between the function of the two sides (well, there is some, and I don't know enough about the anatomy of the brain to go into detail)

[morkendi]

Reasoning is something like writing. We write with a certain hand. Most people are not ambidextrous. You are more proficient with one but still able to do it with the other. Just need the setting to feal like things are not quite rite.

[MesiDoomstalker]

The differences between right brain and left brain function is not entirely related to kinethesis (that is your bodily awareness, which is being inverted in this mirror realm). Most of the differences have to deal with things like language or specific autonomic functions that wouldn't be bothered with a mirror world. The main thing you need to answer here, is the mirror world distorting your perception, so things look mirrored, or are things physically mirrored? That is to say, if your brain instruct your neck muscles to look to your left, does the mirror world invert that command, making you look right, or does the mirror world warp your senses to feel and look like your look right?

If it is inverting your nervous system so commands to your muscles go to the opposite side of the body, then penalties would be appropriate. If your perception is simply being inverted, then it would take mere minutes to adjust to the altered perception. At worst, it would cut your dexterity mod to AC and Reflex saves, since those are instinctual responses that don't take time to think and adjust.

[IZ42]

Reasoning is something like writing. We write with a certain hand. Most people are not ambidextrous. You are more proficient with one but still able to do it with the other. Just need the setting to feal like things are not quite rite.

I'm very strongly left-handed, and have trouble many things with my right hand. However, due to my martial arts training, I am able to do most weapons things with either hand, and probably haven't been training half as long as most D&D adventurers, though I still lead mostly with my left.

Writing does not use the same muscle groups or even the same region in the brain as writing. Sure, there is some overlap, but on the whole, swinging a sword (or throwing something) uses the large, macro groups of muscles, like your bicep, tricep, etc., while writing (or playing the cello) uses the smaller muscles, like the flexors.

[ShaneMRoth]

In upcoming campaign, bad guy will be using mirrors to enter an extra dementional kind of place. The characters will end up going in as well. The idea is their conscious mind will go into the mirrior immage. The thing is everything on there mirror immage is opposite. Sword is now in left side instead of right. So the bodies muscle memory will be opposite of what the mind is used to. I am thinking just a 10% chance to fail any action, thus not to drastic. They will occasionally fail, but still able to do what they want most the time.

I strongly recommend against this.

This isn't even in the same quadrant of the galaxy as fair.

As to the notion that this is not too drastic?

A ten percent failure rate on any action?

You are, at a minimum, statistically doubling the failure rate of rolls. Specific exceptions aside, players already have a 5% failure rate 'baked in' to the game.

Ten percent of Natural 20s would miss?

Your players have to roll a Natural 20 and then they need to roll better than a ... 2? Then they make a threat roll?

Mechanically, that's a critical hit in reverse.

I'm pretty sure that 100% of attacks that always miss (a Natural 1) will miss 100% of the time.

No good can come of this.

[Nibbens]

Reasoning is something like writing. We write with a certain hand. Most people are not ambidextrous. You are more proficient with one but still able to do it with the other. Just need the setting to feal like things are not quite rite.

Agreed, this should be done through description, setting and story telling. Not extra rolls or penalties. Maybe describe their "misses" in combat as "left-brain/right-brain" befuddery.

[morkendi]

The differences between right brain and left brain function is not entirely related to kinethesis (that is your bodily awareness, which is being inverted in this mirror realm). Most of the differences have to deal with things like language or specific autonomic functions that wouldn't be bothered with a mirror world. The main thing you need to answer here, is the mirror world distorting your perception, so things look mirrored, or are things physically mirrored? That is to say, if your brain instruct your neck muscles to look to your left, does the mirror world invert that command, making you look right, or does the mirror world warp your senses to feel and look like your look right?

If it is inverting your nervous system so commands to your muscles go to the opposite side of the body, then penalties would be appropriate. If your perception is simply being inverted, then it would take mere minutes to adjust to the altered perception. At worst, it would cut your dexterity mod to AC and Reflex saves, since those are instinctual responses that don't take time to think and adjust.

This is what i am talking about. The normal brain thinks raise your right hand, but mirrored body raises left. It is not the charaters real body that their consciousness will be in, but and exact mirror image of it. Someone swings a sword at you and your brain however instinctual it is raise your right hand to block, but you mirror immage raises left hand. It would be very confusing.