Whenever I have Cleo in my team (in this case battle of honor), I try to make the most of her passive to help anyone whose crit isn't high enough. I did get her wings so that I could make it better but for a build, I still want her to help her teamates in any way possible while still being able to take some hits. For one star, I would recommend something like slime king, but if you don't have it, spirit of cold steel isn't too bad of a replacement. Her two star can just be something like green ranger, and her third should be shadow corps to help out a little more with her passive. I think defender of earth really helps her because it gives a lot of hp and defense, and the condition is that at least 2 members have to be alive, and the main reason I would even have her is to help her allies, so that shouldn't be a problem. I like to put angel knight on her too because it gives her even more hp and helps out with her pretty bad attack that she'll have because she doesn't have any other sets that really boost her attack, and really, many people have this set now ever since Nexon did that little giveaway. As for potentials, just give her the usual like attack, damage, crit rate and crit damage all by a % on her weapons, defense (both flat and by a %) as well as hp and hp recovery on her armor, and attack by hp, crit by defense, and maybe mp as well as anything that is special to an amount of stars on her accessory. Like this, you can trust her to help out her teamates out for as long as possible.