2d10 is a cool new system for running tabletop RPGs

General Overview

Skill Checks

All skill checks are 2d10 + proficiency + ability + magic + other. Unless otherwise specified, multiple magical effects that add to a die roll overlap rather than stack. “Other” generally comprises penalties from armor check penalties, fatigue, and other sources. The result is then compared to the Difficulty Class (DC) of the attempted action in the case. This may be a static number in the case of an individual action, or the result of an opposed check if it is a contest between multiple characters.

Successes and Failures

If the result meets or exceeds the DC, the check is a Success. If it exceeds the DC by at least 10, it is a Critical Success. If it is below the DC, it is a Failure, or a Critical Failure if it is at least 10 below the DC. For example, if the DC is 15, a Critical Success would be 25 or higher, a Success from 15 to 24, a Failure from 6 to 14, and a Critical Failure at 5 or below. A tie is considered a success for a non-contested action. In the case of a contested action, a tie is a success for the party that rolled second (in most cases, the defender), since the initial roll (e.g. the attack roll) sets the DC. In the case of simultaneous rolls where there is not an identifiable aggressor, a tie represents a tie or no change.

Degree of Success or Failure

Rather than fitting into four categories, some rolls have more variable outcomes, called the degree of success or failure. If your check exceeds the DC, your degree of success is equal to your check result minus the DC. If you fail to meet the DC, your degree of failure is equal to the DC minus your check result.

Advantage and Disadvantage

Many abilities and maneuvers will grant you advantage or disadvantage. When you have advantage on a roll, you roll an additional d10 and disregard the lowest die, whereas when you have disadvantage you roll an additional d10 and disregard the highest die. Advantage and disadvantage stack up to three times, which would involve rolling 5d10 and taking the highest two results or lowest two results, respectively. Advantage and disadvantage are subtractive, meaning that if you have two sources of advantage and one source of disadvantage, the disadvantage cancels out one advantage and the net result is that you make the roll with advantage.

Supporting an action

One common method of gaining advantage is supporting an action using another skill. For example, an inspiring ally may attempt to support a party member’s Traveling check with their Leadership by giving a pep talk. When attempting a Support action, make a check with the supporting skill. In most cases, the DC will be 10, but the GM may determine a higher or lower DC depending on the difficulty of the task or the salience of the supporting skill, as well as whether the support attempt is possible. For example, an artificer attempting a very difficult Arcana check to reprogram an eldritch machine may not find the party minstrel’s inspirational comedy routine to be particularly helpful.

Should the support attempt be made, the typical results would be:

Critical Failure: The target suffers disadvantage on their action.
Success: The target gains advantage on their action.
Critical Success: The target gains double advantage on their action.

An action may be supported by as many allies as is reasonable, though there may be diminishing returns to using the same supporting skill multiple times. In combat, certain abilities or actions may allow you to support either your own or an ally’s actions.

Limiting Skills

Sometimes the ability to perform an action is limited by your capabilities in a separate skill, this is called a limited roll. In such a situation, you roll both skills and take the lower result. For example, defensive combat maneuvers against an attack from behind may be limited by your Combat Awareness, and a Persuasion check may be limited by your Etiquette. In some situations, a separate character may be able to perform the limiting skill check. For example, if a character is foraging in Lamannia, the results of their Provision check may be limited by the results of a Knowledge (Cosmology) check made by either themselves or an extraplanar guide.