Dice Required:
A player of Nutshell Fantasy will require a set of the standard polyhedral dice in all of the platonic solids: d4, d6, d8, d12, and d20.
The GM will require fewer types of dice: d6, d10 and d% (or d100), and d20.
In both cases, it may be beneficial to have multiple dice of each type.
The Core Mechanic
As with the generic d20 System, the Core Mechanic is as follows:
Roll d20 + modifiers
If the result is equal to or higher than the Difficulty Class, the task succeeds. If not, it fails.
Difficulty Classes
Where the target of an effect is a creature, the difficulty class will be one of that creature's defences.
For most other tasks, the difficulty classes as follows:
Descriptor Difficulty Class
Laughable 0
Trivial 5
Routine 10
Average 15
Difficult 20
Hard 25
Extreme 30
Godlike 35
Impossible 40
(Bad formatting, I know!)
It should be noted that a DC of 30 represents the upper limit of real-world human achievement. It is at this level that World Records fall, that the boundaries of science are pushed back, and so forth.
A DC of 0 is something that a character can probably do in his sleep.
When Not To Roll
Typically, characters do not need to roll for tasks with a DC of 10 or less. Occasionally, in high-stress situations, the GM may require a roll even for the simplest task.
"Take-10"
In most cases, rather than rolling the dice you can elect to simply accept a result of 10. This eliminates any possibility of both critical success or critical failure (see below), but may be enough for regular success.
To take-10, simply treat the result of the die roll as '10'. Add the modifiers as normal, and compare with the Difficulty Class.
In stressful situations, such as combat, you will generally not be able to take-10. You are never required to take-10.
"Take-20"
If time and conditions permit, your character may want to be sure of applying his best efforts to a check. In such a case, he can take-20 to get the best possible result.
Taking-20 requires that the character expend 20 times the normal time, and 20 times the normal resources, involved in a check. Additionally, you can only take-20 in those situations where a retry would normally be permitted, and cannot take-20 in stressful situations.
If there are any negative consequences associated with failure in a task, you will automatically suffer these consequences if you take-20. Additionally, in some cases these consequences will make it impossible to take-20. (For example, when climbing a cliff, the 'negative consequence' is falling off. Obviously, falling off means you fail to progress up the slope, and so taking-20 is impossible.) It may not be obvious before you try that taking-20 is not allowed.
You are never required to take-20.
To take-20, simply treat the result of the die roll as '20'. Add the modifiers as normal, and compare with the Difficulty Class. However, this is not considered a natural 20, and so neither automatic success nor critical success apply (see below).
"Take-0"
If your skill with a task is sufficiently great, and the task sufficiently easy, you may elect to take-0. Unlike taking-10 and taking-20, you may take-0 at any time. However, you are never required to take 0; you may always elect to roll if you want the possibility of critical success.
To take-0, simply treat the result of the die roll as '0'. Compare your total modifier against the Difficulty Class as you would normally.
Automatic Success or Failure
In general, a result of a natural 20 on the die roll indicates an automatic success, and a result of a natural 1 is an automatic failure.
Again, in the case of extreme results, this rule may not apply - this would generally apply if even a roll of 25 would not be enough to succeed, or a roll of -5 would still be enough for success.
Critical Success or Failure
Some rolls may allow the possibility of critical success or failure. Note that not all rolls allow this, and that some rolls may allow critical success but not failure, or vice versa.
If critical success applies to a roll, then when a natural 20 is rolled on the die, this is considered an automatic success, and a potential critical success. At this point, you should make a confirmation roll.
In most cases, a confirmation roll is simply a case of making exactly the same roll again, with all the same modifiers, against the same Difficulty Class. If the confirmation roll is a success, then a critical success has been scored. If the confirmation check fails, then only a normal success has been scored.
In general, a critical success will have double the effect of a normal success. Roll the magnitude check as normal, but roll double the dice and add double the modifiers.
If critical failure applies to a roll, then when a natural 1 is rolled on the die, this is considered an automatic failure, and a potential critical failure.
At this point, you should make a confirmation roll, as described above. If the confirmation roll fails, then a critical failure has resulted. If the confirmation roll succeeds, then disaster has averted, and only a normal failure results.
In general, a critical failure will have double the effect of a normal failure.
The rules for automatic success and failure, or critical success or failure, do not apply to confirmation rolls.
"Natural Even"
In some few cases, a check will specify that it can only be passed on a "natural even" result. In such cases, roll the check as normal. However, in order to pass the check, the character must not only beat the Difficulty Class, but the value shown on the die must also be an even number.
Degree of Success and Magnitude Rolls
Sometimes, it is enough merely to know whether a task succeeds or fails. Often, however, it is important to know how well a check has succeeded, and so a Magnitude Check is required. A Magnitude Check works just like a damage roll in most games - you roll dice and add a modifier to the check.
By default, magnitude checks are rolled on a d6. This assumes that you have the standard tools required for the job, and decent conditions to work with. For example, when picking a lock, if you have a standard set of picks, you may roll a d6 as your magnitude check.
If you are forced to work with poor or improvised tools, the magnitude check may be reduced to a d4 or d3, while superior tools and training can increase the check to a d8 or even d12.
In all cases, you apply the same ability score to magnitude checks as applied to the original check for success or failure. For example, most characters apply their Strength modifier to melee attacks rolls and they also apply their Strength modifier to the resulting melee damage rolls; however, a character with the Weapon Finesse feat applies his Dexterity modifier to some melee attack rolls, and also to the resulting damage rolls.
Nominal Success and Imperfect Defences
Some powers and spells grant an "imperfect defense" against particular attacks, reducing that attack to a nominal success. Alternately, some effects may reduce a character's effectiveness to a "nominal success". (A nominal success on an attack roll is called a "glancing blow".)
If a nominal success is scored, treat all the dice in the magnitude check as if they had come up as '1'. Apply any modifiers normally. In effect, a nominal success has the minimum possible effect that could be generated using the dice.
(For example, if a Fighter attacks with his sword for 1d8+4 damage, on a glancing blow he will do 5 damage - the minimum that could be scored. Similarly, if a Wizard throws a fireball for 5d6+12 damage, on a nominal success he does 17 points of damage.)
Note that even a critical success can be reduced to nominal success in this manner!
Modifiers, Step Changes, and Extra Dice
Frequently, the game will award modifiers to rolls. Indeed, almost every roll you will make will include a modifier from an ability score, if nothing else. Modifiers are given in the normal notation, as +X or -Y, and should simply be added to the roll. Any effect that does "double damage" or similar also applies double the normal modifiers to the roll.
Somewhat less frequently, the game may apply step changes, adjusting the die type of a roll. For example, the Weapon Specialisation feat applies a 1 step increase to the damage caused. In this case, you should substitute the dice used by the next size up.
The progression is as follows: d3, d4, d6, d8, d12. The smallest die type that can be used is d3; any step changes down from this value should be ignored. The largest die type that can be used is d12; any step changes up from this value instead add a +2 modifier to the roll.
The d20 is never subject to step changes. That is, the d20 can never be changed to another die type, and neither can any roll 'step up' to use the d20.
Finally, some effects (such as sneak attack) add extra dice to a roll. In most cases, the effect will indicate which dice should be added. However, if the power merely says "add 2 extra dice", without specifying a die type, add extra dice of the largest type that are already being rolled. That is, if you are using a weapon doing d8 damage, add an extra d8; if using d12 then add an extra d12, and so on.
When rolling a critical success, extra dice are always added first. Thus, if the critical does double damage, you may roll double the entire damage pool.
The d20 is never affected by extra dice. That is, the d20 will never be added to another dice pool, and neither will you add another die to a d20 roll.
Rerolls
Some effects will give you the opportunity to reroll a die or dice.
You may announce your previous result before applying a reroll, and may even hear if your attempt was a success or failure before rerolling. However, you must declare your reroll immediately at this point; if the results have been narrated, you cannot use a reroll to "take it back".
If you choose to reroll when you initially rolled multiple dice, you may choose to reroll all of the dice, or only some. (Note, however, that if you made two rolls at the same time, such as rolling an attack and damage roll together, these are still considered separate, and so you much reroll each separately.)
When you reroll, you must accept the new result, even if it is worse. No roll can be rerolled more than once.
Some powers allow characters and creatures to force others to reroll. If you are subject to such a power and you have a reroll of your own, you may expend your own reroll to negate the targetting power. In such a case, both rerolls are expended, and the initial result stands. But, again, you must do so before the dice are rolled for the second time. (Remember: no roll can be rerolled more than once.)
Note that you can only reroll, or force a reroll, when dice are actually rolled! If you take-10, for example, you cannot then reroll.
