Originally Posted by
MisterBob
It's easy if you understand Rafa's AI. If you put a chemist on the back part of the roof where your party starts, Rafa will run directly to it at the start of the fight, instead of running out to Celia and Lede.
Also, you don't even have to kill one of them. Critical HP is enough (they kneel when they are at critical).
If you're not extremely overleveled though, its going to take at least 4 attacks to take a single one of them down that low, and chances are they are going to act a LOT faster than you, unless you have a party of Ninjas.