I mentioned in my initial post on this project that one priority here was a system that could easily accommodate homebrew bending styles. And obviously, representing different bending styles in general is going to be important here. You don't want all waterbenders to play the same, especially when one of avatar's strongest themes is the intertwining relationship between cultures and bending styles.
So here's how this Avatar RPG will represent bending styles: Three-feat chains. Taking yet another cue from my d20 Rethought project, bending styles will be represented by collections of feats that in turn each grant several bending techniques. Each style of bending will have a "core" 3-feat chain dealing with the simplest (though not always easiest) applications of a technique. And each bending style will have an associated skill as a prerequisite. For example, Earthbending Basics will require 2 ranks in Stance, Earthbending Expertise will require 3 ranks in Stance plus the character being at least level 4, and Earthbending Mastery will require the character having 4 ranks in Stance plus being at least level 7 (out of theoretical 'maximums' of 5 skill ranks and 10 levels).
As a side-note, I should credit Spycraft with the idea of giving feat chains a naming chain whose alphabetic order matches their heirarchy- all 3-feat chains will use the Basic-Expertise-Mastery naming method. There will also be some specialized applications of bending that require only a single feat (such as Lightning Bending for firebenders), as well as ones that also require a Major or Minor advantage just to take the feat (for bending uses that are considered rare talents, such as using waterbending to heal or wielding blue fire.
Last but not least, I plan to set a single feat aside specifically for making your own signature move, as an "in-between" for those who just want to be able to do something special on a reliable basis. Examples of a special move include Hugh's plant constructs and Iroh's lightning redirection.
To return to the original topic: this setup should make it very simple to write up balanced rules for whatever custom bending ideas you have in mind. An airbender who manipulates chakrams like guided missiles? A waterbender who learned a different style based around the concept of wearing down enemies through a sustained application of force? Go for it!
For the next post, I'll actually have a rough draft of the full list of the different bending styles the game will offer.
Art Credits: Image by z00tz00t.