|The name of the build says it all: pick a 4* Clarine, inherit Fear, Martyr and Swift-Winds Balm to Priscilla. Then pick a 5* Clarine and inherit Fear+ and Martyr+.
This build does two things in a very good way. You can either power up the bulk of your team by attacking safely (if you have Dazzling Staff) and debuffing enemies with Fear+, or you can bulk up your team's speed, thanks to the combination of Swift-Winds Balm and Drive Spd (if you're using a mixed team)/Goad Cavalry (if you're using Horse Emblem). Fear+ also allows Priscilla to take hits pretty easily, and her high speed will stop enemies from doing follow-up attacks on her. Remember: speed is the best defense.
Jokes aside, there's not much to say about this build, it does its job very well and HP +5 as a seal allows Priscilla to tank hits pretty well, but you can run Ploys safely if you wish.
Martyr works much better than Rehabilitate on her, thanks to the fact that she tanks really well (especially mages), and personally I prefer it in general as it allows your healer to stay alive longer, and it's a strong heal skill overall. A 5*+0 Priscilla will heal 20 HP if she's at full HP, and the more damage she'll suffer, the stronger the heal will become. If you prefer Rehabilitate, however, she comes with that so there you go.
Build made by @DeadInscyde (twitter)