D&D Homebrewery Guide - Sub-Classes

Sub-Classes are more appropriate for class ideas that are better suited to being an Archetype of an existing class. This could be because your idea is not or cannot be fleshed out to the point of being its own class or because your idea has too much overlap with the core elements of another class.

For example: Your class idea may have a lot in common with the core elements of the Fighter class but has some unique abilities that spring up along the way. This indicates that it may be better to make your idea a sub-class of the Fighter class.

There are many other reasons why your idea may be suited to being a sub-class rather than a class or any other element such as a background for D&D, but nevertheless - you are here.

For starters, go check out the series done by D&D Beyond about creating a sub-class that starts with this video.

Theme
Just like a class, any given sub-class needs a theme. Think of the Hunter and the Beastmaster sub-classes of the Ranger class both have different themes that make use of the core class. So you have to decide on a theme that your sub-class will have.

Pattern & Precedent
Take a look at how the other official sub-classes of the class you are creating for. They will generally follow some sort of pattern. For example: The second Archetype Feature given by the sub-classes of a particular class may all give a proficiency in something.

Also look for similar abilities to your own ideas in other sub-classes. Do your ideas tread to close or onto other ideas found in other sub-classes?

With that in mind, look for the precedent in what your ideas are and look for the formula in the official sub-classes.