New to Modding - Advice Sought

[MsFicwriter]

Hi there! I want to make a Druid subclass with a spider shapeshift and extra penetration on Decay spells. I've never modded anything before, so how do I go about this?

Thanks! 

[omgFIREBALLS]

As luck would have it, someone recently posted on Discord about a huge mod that does things like this. Maybe they could help you in exchange for some playtesting.

[MsFicwriter]

Hmm. For some reason, I can't access the thread. Discord says I have "no text channels."

[omgFIREBALLS]

Ah right, you need to go to channels and roles and select Pillars of Eternity to be able to see those channels.

It's the Obsidian Discord server, so it shouldn't be hard to find if the link doesn't agree with you.

[Kvellen]

Hey, sorry for the late reply!
A good place to start is the modding documentation that Obsidian themselves provided, and the Apotheosis mod tool by Noqn. The modding documentation is pretty intimidating at first but does a pretty good job explaining purpose of most of the game data contained in the .gamedatabundle files. Where as Apotheosis is built for exploring and working with that game data in a way that is much more approachable than having to format and parse those .gamedatabundle files.

Otherwise if you have any questions about how to do more specifics things feel free to ask!

On 11/17/2025 at 7:46 PM, MsFicwriter said:

I want to make a Druid subclass with a spider shapeshift and extra penetration on Decay spells. I've never modded anything before, so how do I go about this?

Thanks! 

So board strokes:

Characters -> CharacterSubClass.
This is where you set up the basics of a new Subclass entry.

Abilities -> GenericAbilities and StatusEffects -> StatusEffect
My advice would be to duplicate existing abilities and status effect that are close to what you want and make the necessary tweaks to those. Some of the data types for abilities and their parameters can be a bit confusing to navigate when making them from scratch.
So maybe duplicate something like "Spiritshift_Cat" and make changes to a spider model, and for the decay penetration duplicate something like Heart of the Storm and change the keyword for the Attackfilter to on the status effect.

ProgressionTables -> BaseProgressionTableAppend
This can be a bit complicated to explain. Depending on what you are trying to do. A new BaseProgressionTableAppend is the best as far compatibility with other mods, when it comes to adding new abilities and features to a class, as these addition are additive to the existing class progression tables.
However from what I can tell it doesn't support conditional subtractive edits. Such as setting restriction on existing abilities (such as losing access to certain base class abilities like with the Watershaper with fire abilities for example) for a new subclass. These types of edits may require making edits to how conditions for abilities unlocks on ClassProgressionTable.