2d20 Mod part 2, Basic rules

Basic rules of 2d20

These rules are deliberately a bit brief. If you want detailed rules buy one of the Modiphius games!

Rolling Dice

  1. Work out the TN. 
    1. This is equal to the character’s attribute plus relevant skill that is relevant to the task.
  2. GM sets the difficulty. 
    1. 0 to 5. 
    2. 1 is the standard difficulty.
    3. Adjust the difficulty based on any relevant traits
  3. Players takes 2d20. 
    1. Player may buy extra dice 
    2. up to 3 extra
    3. By spending Momentum
    4. By adding to Threat
    5. By using Fortune
    6. Roll the dice!
  4. Each die that is equal to or less than the TN is a success
    1. A 20 is a complication
    2. A 1 counts as 2 successes
    3. If a focus is applicable, and the dice is equal or under the linked skill, that dice counts as 2 successes.
    4. Fortune sets a dice to 1 ( so granting 2 successes)
  5. If the number of successes is equal to or greater than the difficulty, the task succeeds
    1. If it is less than the difficulty, the task fails
    2. Extra successes beyond the difficulty are converted into momentum
  6. The GM describes the outcome of the task
    1. A player may spend momentum to improve the result further
BR Mod 1.1 Focus is a statBR Mod 1.2 No skills 
If your focus is rated, not a specialisation, then you score double when you roll equal to or lower than the focus. In this case a 1 does not grant double successes.If you only have attributes you add two attributes together to get your TN. And rolling equal to or under the lower attribute grants double successes.

Taking Action


When a character takes an action to complete an activity where the outcome is in doubt, they make a test. Follow the procedure for rolling dice, above.

Opposed tests

When a character attempts to compete with, conflict with or attack another characters (PC or NPC) they both characters make opposed tests. Each character tests against difficulty 1. 

Active character succeeds, reactive character fails – Active character succeeds in their goal, outcome depends on the action in question.

Active character fails, reactive character succeeds – Active characters fails to achieve goal. Reactive character may get a benefit depending on action.

Both characters fail – Active characters fails to achieve goal. Reactive character gets no special benefit.

Both characters succeed. Whichever character achieved the most momentum on their roll succeeds. Subtract the losers momentum from the winners momentum. In the case of a tie, the Active character succeeds (but has no momentum).

Complex tests

A complex test may require multiple skill tests and in addition to a difficulty has a momentum requirement. The test is only completed when the player/s have gained enough momentum as the requirement. The test may have a time limit on it and consequences for rolling complications.


Momentum is earned by beating the difficulty on a test

Momentum can be spent as follows:

  • Buying extra dice for a test
    • The 1st dice costs 1 momentum, the 2nd dice costs 2 momentum and the 3rd dice costs 3 momentum (so 6 total)
  • Create a Trait
    • You spend 2 momentum to create a new trait, or remove an existing trait. The skill test must be relevant to the trait.
  • Obtain Information
  • Reduce Time 

If you have Momentum left over you can add it to a group pool. The group pool can store a maximum of 6 momentum. At the end of a scene the GM removes 1 point from the group pool.

BR Mod 2.1 cheap diceBR Mod 2.2 No Group Pool
Instead of increasing the cost of additional dice, additional dice always cost 1 momentum.Players can store their own momentum, there is no group pool.


You start an adventure with 2 Fortune points

You can earn more Fortune from good roleplaying , or completing objectives.

You can spend Fortune as follows:

  • Critical Success. Add an extra dice to a test and set it to 1.
  • Reroll. You may reroll any number of dice in a test (or damage roll)
  • Additional Action. You get an extra action!
  • Avoid Death. When you should die, spend a fortune point to somehow avoid death.
BR Mod 3.1 Different namesBR Mod 3.2 More or less
Fortune is named luck or determination or something elsePlayers start each session with more or less Fortune, or it is linked to an attribute or skill


The GM starts a session with 2 threat per player.

The GM spends threat like momentum, but also has additional spends.

The GM can earn more threat by banking threat from an NPC roll but also when players buy extra dice using threat. If a player wants extra dice, but doesn’t have enough momentum they can use threat instead at the same cost (so a 3rd additional dice costs 3 threat).

BR Mod 4.1 Different namesBR Mod 3.2 No Threat, just Momentum
Threat is named Doom or Danger or something elseThere is no threat, there is only momentum. In this case GM has their own momentum and players can buy dice using their momentum or by giving momentum to the GM.

Traits and complications

Traits describe important facts. They can be location traits, situation traits or personal traits. A trait makes an action easier or harder (changing the difficulty) or possible or impossible. Traits can also be rated. E.g. smoke 2.

When a player rolls a 20 they cause complications. These are temporary traits. A player suffers a complication they can always choose to remove it by adding 2 threat to the pool instead.

A player can also generate a complication when they fail a test, but the GM allows them to succeed at a cost.

BR Mod 5.1 No TraitsBR Mod 5.2 Traits, in name only
Traits are not a thing, they do not exist.Traits exist, but in name only. They are for RP purposes, and have no rules attached.

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