Kessen is the best hero in this game for many reasons. I love him, and I don't care about SW hardcore fans that keep saying he never was in the OT and is a Disney creation, or whatever. He's good for both faction, now even better for Rebels after the training time being reduced to the same training time of the Imperial Kessen. What makes him available for sucessive attacks like the eAT-AT.
I think there are other veterans with more tips about Kessen than me, but even at low levels Kessen can be very useful in wars and PvP thanks his magnetic shot.
You can blow walls with that shot to open holes to infiltrate units, you can hit that damn droid hut that is left in the opposite corner before time runs out, you can use him to kill enemy troops, and of course you can blow SC and everything else in the way of his magnetic pulse.
All you need to do is align Kessen with some building in the straight line with the SC and shot (look if his riflle Karina is in the right direction or he can miss the shot), and use live dekas if they are available in the enemy base to align with the SC -- dekas are Kessen priority target. Use a Luga to increase the power of his shot against higher level targets.
Don't miss that shot or Kessen becomes useless. Have always a Plan B. Kessen requires a lot of practicing, but once you get the point, you will love to use him, and get trust in give that shot. Sometimes he fails, and even if you see the shot passing through the SC you can't destroy it. The line created by the shot is not accurate, you can think you hit but sometimes you don't. That's what I see when I use Kessen.
SWC Windows survivor.
Imperial HQ 11 & Rebel HQ 11 on vacation.