u/AndrewPLayerXD

Gunnar is a campaign exclusive hero with specialization that allows him to use heroic strike unlimited number of times per round, the only thing that limits him from doing that are focus points, but advanced combat skill allows you to pick subskill that reduces the cost of heroic strike by 1 focus point, so basically to 0. With a little bit of luck with skills (unless combat skill is excluded from the campaign) you can win every battle, even on highest difficulty just by spamming heroic strikes. I'm writing "in theory" because at the moment I'm unable to confirm if this really works that way.