Expression Syntax

Expressions are evaluated at runtime using the monster’s stats. The parser supports numbers, dice notation, ability modifiers, operators, and functions.

Basic Elements

Numbers

5
42
-3

Dice Notation

2d6      # Roll 2 six-sided dice
4d8      # Roll 4 eight-sided dice
1d20     # Roll 1 twenty-sided die
10d10    # Roll 10 ten-sided dice

Ability Score Modifiers

Use lowercase ability abbreviations to reference modifiers:

Token	Ability
str	Strength
dex	Dexterity
con	Constitution
int	Intelligence
wis	Wisdom
cha	Charisma

Caution

These return the modifier, not the raw score. A Strength of 16 returns +3.

Special Variables

Token	Description
prof	Proficiency bonus (derived from CR)
level	Creature level (typically 0 for monsters)

Operators

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division

Operator Precedence

Standard math precedence applies:

1. Parentheses ()
2. Multiplication and Division *, /
3. Addition and Subtraction +, -

Functions

max(a, b)

Returns the larger of two values:

max(str, dex)        # Higher of STR or DEX mod
max(10, 8 + prof)    # At least 10

min(a, b)

Returns the smaller of two values:

min(str, 5)          # Cap at +5
min(dex + prof, 10)  # Maximum of 10

Grouping

Use parentheses to control evaluation order:

(str + prof)         # Evaluate together
(2 + 3) * 2          # Evaluates to 10
str + (prof * 2)     # Double proficiency added to STR

Expression Output

When an expression is parsed, it produces a result object containing:

{
  dice: { d6: { numberOfDice: 2, die: 'd6' } },  // Dice components
  avgResult: 7,                                   // Average expected result
  expressionValue: 3,                             // Non-dice component
  expression: "2d6 + str"                         // Original expression
}

This allows the system to:

• Display the average value
• Roll the dice when needed
• Show the original expression