Custom Combat Mode

Is it at all possible to set up a custom combat mode?
Not asking about difficulty of creating but how easy it would be to integrate. How hacky will the integration be?

Depends on what you mean. There are several fanmade combat systems available through plugins etc.

Yes.
Everything depends on the features and on how much of the defalt mv code you intend to keep. If you want, you can completely scrap MV's code - for which the integration would be easy. However, it gets more difficult if you intend it to work with other battle systems and 3rd party plugins.

The most important question is this: do you know how to code? If you can, you can not only create your own battle system, but you could also keep part of the default battle code and integrate it easily, provided you're ready to spend time on it. If you can't code, now that becomes tricky, since you complete depend on third party plugins. You could always look for a totally custom battle system free plugin, or mix different plugins that changes an aspect of battle. Now the trickiest part is making everything work and being compatible.

Thanks everyone. I do know how to code and I was mostly interested in how hard it would be to work around the default code so its good to hear that I can just remove it if I need to.