Well, True, i understand de overhyped this ML 5* weakness... ken aggressiveness comes mainly from his passive S2 & 4 turns S3, which means he is best played by players not by AI, and so he doesn't need to be fast, just need to be deadly & self sustain with leechin' (unless you can get super duper gears with hp%,Def%, Atk%, Effect Resist%)... And this is actually a dang trap, it's a big no no in arena defense team, just like his fire counterpart, Defending AI is never good at handling these 2 units...
in fact, you don't need Axe God or whoever can def break, Sigret or Watcher Schuri who can penetrate defense do him easy as well...
Effect Resistance is also important for ML Ken or else A.Cartuja whoever can stun, and unhealable debuff can be a big problem to his self sustain, to a minor degree, de Decrease Hit Chance+Decrease Atk can make his S2 hit like pussy... He is just not good on defensive game, but he is a good active AND passive offender that only players knows how to handle or deal with... F.Kluri is a pure defender+supporter, very different role and they may go well with each other... may be he plays a scarecrow role as defender...
Anyway, F.Kluri skill tree is too much for me now, i have to gear up my team, since her alone can't really carry me through harder content...
For Pve content you can mostly ignore her since you already have ML Ken and other hero who can Def break.
By the way i saw some leak on new continent Heroes. so maybe time to clear 10-10 world difficulty and embrace new continent content LOL