woah parrott i need to put down my drink. I can do this myself?
Yes, and it is quite easy to do. Just copy a champion you would like to model into another file. Tweak some things (change the internal name), put this new file into your mods folder and there you have a new champion when your run your mods. The game will pick up the new internal name for the unit type and there you go.
You can copy some monster and make them into a champion by adding the tag <IsChampion>1</IsChampion> to the file.
The abilities work the same way, it only takes some time to learn the system they use to add effects and abilities in the game (it is quite accessable).
***WARNING: if you plan on changing any of the core files, back them up so you can replace them*** (less of a warning because steam will fix anything you break anyway, but you might not want to wait for the update to download).