If you have a model (eg. Bilbo/Frodo) who halves someone's fight value by being invisible, and the enemy strikes, do they strike up (eg. from six to ten) then get halved to five, or do they get halved to three, then then can strike up (potentially going back up to nine for example).

I think it's the first one, but I couldn't find it in the book when I was looking.

Ah, I found the answer to this now ...

It says in the heroic strike section that they increase their fight value first, then get halved afterwards.