how to chasnge attack formula foundry

3 min read 23-01-2025

Foundry Virtual Tabletop (Foundry VTT) offers incredible flexibility in how you manage combat. One key element of that flexibility is the ability to customize your attack formula. This article will guide you through changing and understanding your attack formula, enabling you to tailor your combat system precisely to your needs. We'll cover everything from basic adjustments to more advanced modifications.

Understanding the Attack Formula

Before diving into how to change it, let's understand what the attack formula represents. In Foundry VTT, the attack formula governs how damage and other attack-related effects are calculated. It's a string of text using a specific syntax that Foundry interprets to determine the final result of an attack. The default formula often looks something like this: @damage + @bonus. Let's break it down:

@damage: This represents the base damage die roll (e.g., 1d6, 2d8). This value is pulled from the weapon or attack definition.
@bonus: This represents any modifiers added to the attack (e.g., strength modifier, proficiency bonus). These modifiers are typically set within the actor's character sheet.

Modifying the Attack Formula

The location to change your attack formula depends on your system and setup. The most common places are:

1. Item Properties

The most straightforward way is to change the formula directly within the item's properties.

Open the Item: Navigate to the item (weapon, spell, etc.) you wish to modify within your Foundry VTT world.
Find the Attack Formula Field: Depending on your system, this field may be labeled differently. Look for fields like "Attack Formula", "Damage Formula", or something similar. It's often located in a tab labeled "Details" or "Data".
Edit the Formula: Replace the existing formula with your desired one. Ensure you use the correct syntax (explained below).
Save Changes: Save the changes to the item to implement the new formula.

2. System Settings

Some systems offer more global control over the attack formula, allowing you to modify it for all items using a particular system. Check your system's documentation for instructions on how to do this. This is often found within the system's configuration settings within Foundry.

3. Macros (Advanced Users)

For advanced users, macros provide an even greater level of customization. You can create custom macros that calculate damage in more complex ways and then integrate these macros into your attack formula.

Syntax and Common Adjustments

Foundry VTT uses a specific syntax when defining attack formulas. The core elements include:

@variables: Foundry uses @ followed by a variable name (e.g., @damage, @bonus, @abilityMod). These variables are automatically populated based on the item and actor. Refer to your system's documentation for a full list of available variables.
Arithmetic Operators: Standard arithmetic operators like +, -, *, and / are used for calculations.
Functions (Advanced): Some systems support more advanced functions that can be incorporated into your formula. Refer to your system documentation for details.

Here are a few examples of common formula adjustments:

Adding a flat bonus: @damage + @bonus + 5 (adds a flat +5 bonus).
Critical Hits: Many systems require special handling for critical hits. You might use a conditional statement (if available in your system) or a separate formula for critical hits.
Weapon Properties: You might include terms relating to weapon properties such as reach, range, or other custom properties.

Troubleshooting and Debugging

If your adjusted formula isn't working as expected, there are a few troubleshooting steps:

Verify Syntax: Double-check for typos and ensure you're using the correct syntax.
Check Variable Names: Make sure the variable names you're using are accurate and consistent with your system.
Console Logging: Foundry's developer console can provide valuable debugging information. Use console.log() to print variable values or intermediate calculation results.
System Documentation: Consult the documentation for your specific system; it will contain information on supported variables, functions and syntax.

By understanding the attack formula and its components, you can drastically improve the customization and realism of your combat encounters in Foundry VTT. Remember to always back up your world before making significant changes!