This allows you to roll for who will win in combat. As this is 'final' it should be the last roll to decide the overall victor. All parties should roll if it's requested (though we'd still rather you just RP'd out your whole combat).
As a general guideline the higher roll wins, with the difference between the roles a good indicator for how close it is.
For groups (either one vs many or many vs many) you take the largest roll on each side and half of the rolls of the rest and add them together for a total.
Technical Note: +final combines all of your styles together, as well as your secondary stats, to come up with the number with a bit of randomness thrown in at the end.