My take is that if you've been lurking for a while and want to do stuff, that's great.
However.
1. Working with Bethsoft's concepts, images and names, let alone art rips, exposes you legally. It's not a great idea; if you got it built after a year of hard work and it was great, you'd get a C&D for a prize; Bethsoft does not appreciate competition.
2. Using something like that as the source pretty much enforces that you do XYZ (a giant list) of design and coding things, let alone content, before players will give you kudos; basically, you've chosen something that would require a large team of reliable experts to assemble.
As an alternative, I'd suggest that perhaps you could build some magic code and start a basic fantasy mod. Just writing a magic system that players (let alone AI) can use will be complicated enough that it will take a lot of work. This engine isn't really designed very well for magic, but you can do it with some work and patience. For example, you can design a magic system that uses special "guns" as the "magic staves"; each gun would execute different code when fired, or their shots would. Code for how to make "guns" behave in special ways, use special animation and generally act in new ways can be found in Blood and Steel's source code, which comes with every release; feel free to read it and use it for whatever you wish.