Can you take a screenshot of the campaign mission you're trying to complete and post it in here? Xena is an attack champ, but it sounds like you're trying to get something with attack % as a main stat to drop. Either way, seeing the mission will help.

how do I do a screen shot?

I finally cleared that mission. thanks

how do I tell which is their primary stat?

i

confused on how to determine the ATK Primary % as primary stat.

This is what it's referring to as the Primary Stat

i

i

 I am having a hard time with this one?

these ones are just luck. it's just a matter of doing the correct stage(s) and getting those bottom row pieces to drop at 4* or higher with HP%.