For any of you that are having trouble with Hard Mode, Jens is going to be your new god.
Any stage with a hill or high ground, climb up the ladder, having 3 character surround the the only opening on top of that hill, enemy that climbs up will be surrounded and killed, if enemy try to find another way up use trap to keep bounce enemy away, fall damage is also no joke, especially in Hard mode, with weapon upgrade, the trap cost only 1 TP. have rest of your unit either rain down arrow or magic.
This works in a lot of stage except for those flat ones, many character have incredible synergy with Jens too. For example use Rudolph trap on that opening space to make any enemy lose its turn when they climb up, he is also a good archer that natural works well with this strategy. Another example is Erador for pushing enemy off cliff if they have multiple entrance of making to the top, he alone could block one entrance. Narve could also create conductive terrain where hey could paralyze enemy in an AOE when they try to find their way up, with Julio to keep the TP up all the time. Also, in this strategy, poison+oil+fire is your best friend as it does not scale down with hard mode and you have plentiful time to wait it out.
This character is extremely broken, he opens up so many possibility with he skillset, and no enemy unit have similar skillset either, making him extremely unique. Imaging if enemy could build ladder and lay traps.
When I first start playing this game, I hate these stage with hills, but now I can't never go back to flat terrain anymore.