The basic procedure is the similar to a Skill check, in that you make a d20 roll (the Domain Action Check, or DAC) against a target number (the Domain Difficulty Code, or DDC). As with other d20 checks, a roll of 20 either counts as a roll of 30 or allows you to roll another d20 and add 20 to that result (player choice). Likewise, rolling a 1 means you get a result of -10, or you must roll another d20 and subtract the number from 0. Note that if you roll a second (or third or more) 20 and keep adding them together it is possible to achieve a truly extraordinary margin of success (or failure).
There is no automatic success or failure rule, but rolling a '20' should work most of the time, while rolling a '1' will almost certainly make the action fail.
Domain Action Check (DAC)
To make a domain action check, roll 1d20 + Action modifiers + Influence.
Domain Difficulty Class (DDC)
To determine DDC of a given action, check the action description to get the base DDC & to determine what modifiers are applicable. The final DDC is equal to the Base DDC + Difficulty modifiers + Influence.
Actions without a DDC.
Some actions do not have a DDC. Such actions are either automatically successful (example: Cast Realm Spell) or have some other requirements that must be met in order to succeed (example: Change Realm Alignment).
Actions without DDCs are never subject to modifiers or influence.
Margin of Success (MoS)
Sometimes it is important to know by how much you succeeded. The number your DAC beats the DDC with is called the margin of success (MoS).
Some actions may provide additional benefits if your margin of success is big enough (typically MoS of 10 and/or 20).
Failing by 10 or more points might also lead to some additional disadvantages, even if failing the action normally does not have any negative consequences.
If you roll a natural 20 AND get MoS of 20+, you have completed the task impossibly well. Check each action description to see whether this provides some additional benefit.
If you roll and natural one AND fail the action OR if you get a MoS of -20 or worse you have done incredibly poorly. Check each action description to see whether this causes some additional drawbacks.
Sometimes two (or more) actions come into direct conflict with each other. In such cases, the action checks are considered opposed, and the winner is the one with the higher Margin of Success (MoS).
∑ Example: There is one holding level available in a province, and two regents successfully rule their holding there. After using influence, regent A has a DDC of 12, gets a DAC of 16, and consequently a MoS of 16-12=4. Regent B has a DDC of 18, gets a DAC of 21, and thus a MoS of 21-18=3. Even though regent B had the higher DAC it is regent A who is able to rule his holding since his MoS is actually higher.
Not every instance of opposing actions counts as conflicting actions. For example, two agitate actions, one positive and one negative, are not affected by this rule. Each is applied separately, possibly cancelling each other out.
Action Checks without Rolls
Instead of rolling the dice, you may chose to play is safe by selecting one of the two options below.
Regents may always elect to Take 10 (i.e. you get a '10' on the d20 roll) on any action, unless otherwise noted in the individual action description.
When mustering troops, moving ships, sending dispatches, etc. it would generally be considered unwise NOT to take 10. HOWEVER, as soon as someone starts using Influence (spending GB/RP) to affect the outcome of the action, the dice must be rolled.
It should also be noted that some actions are inherently uncertain and will ALWAYS require a dice roll (will be noted in the action description). Adventure actions, among others, always require a dice roll.
You may also elect to Take 20 (i.e. you get a '20' on the d20 roll) on Regent Actions. This uses up all 3 base Regent Actions (you can still take your bonus Regent Actions normally) for that turn.
When taking 20, using Influence does not force you to make a dice roll!
Action and Difficulty Modifiers
Some situations may make an action easier or harder, resulting in a change to the DDC or in a bonus or penalty to the DAC.
∑ Example: Itís one thing for the Lord of Fukuchi to Move Ship in the sheltered waters of the Engokai during summer, but quite another to do the same on the Nankai during winter (increase in DDC)
Conditions that affect your ability to perform the action change your DAC. Each action is listed with a number of common modifiers. Influence (positive) is also a major source of DAC modifiers.
Conditions that modify how difficult a task is affect the DDC. Each action description lists a number of common modifiers. Influence (negative) is also a major source of DDC modifiers.
A bonus to your action check or a reduction in the DDC has the same result; they make it more likely that you will succeed. However, they represent different circumstances, and sometimes that difference is important.
∑ Example: The High Priest of the Kiishi sect and the Lord of Oharu are both trying to rule a vacant manor holding in Yunaguni. The base DDC is not very high, but both regents use a lot of Influence (RP and GB) to prevent their opponent from succeeding (using their defensive pools/purses).This leads to a big increase in the DDC (for both domains), resulting in neither regent succeeding. Had they used their influence to support their own actions, instead of opposing the other party, they would both have succeeded, and the one with the higher MoS (Margin of Success) would have been the one to rule up his manor holding.
The Adventure action is best used for resolving events, but can sometimes be used to substitute for other actions. If successful, such an adventure will have some discernible domain-level benefit.
You should, however, keep in mind that you cannot perform miracles using Adventures. Moreover, that in the context of the game you are not supposed to be duplicating the effects of other actions (Agitate, Rule, Contest, or whatever) using Adventures.