I don't think king and ban ever had that much synergy. You'd think strength transfering would make king have insane strength and magic but king would probably explode before he gets a relevant PL. And it does not appear ban can steal magic... Ban is a good tank so perhaps him being on the front lines while king nukes stuff is a good enough combo.
King being able to use multiple chastiefol forms at once does open an interesting possibility though. His sixth form, the armor, could be something that he can perhaps have others wear. Ban wearing the sixth form while king nukes stuff would be an improvement over the previous combo at least. Of course, the question would be whether king can grant the armor to others. Otherwise its not even that good a combo since king could wear the armor for added protection while nuking stuff.
King being able to use multiple chastiefol forms at once does open an interesting possibility though. His sixth form, the armor, could be something that he can perhaps have others wear. Ban wearing the sixth form while king nukes stuff would be an improvement over the previous combo at least. Of course, the question would be whether king can grant the armor to others. Otherwise its not even that good a combo since king could wear the armor for added protection while nuking stuff.