>>399141427
No flipping from what I can see, it mostly happens whenever I bring my forearms up. I'll try the suggestion out. 

>>399141430
Ah I see, thankfully the other anon could back you up. 

>>399141457
You said that I'd need to set up a constraint in Unity, but I'm wondering if following this video would work as well. 
https://www.youtube.com/watch?v=LTQ9gyeaeWI
If that's incorrect I'll just create the twist bones, weight paint them and follow this one https://www.youtube.com/watch?v=_GmAupH5Co0