Board Thread:Questions and Answers/@comment-24.4.157.162-20141118011417/@comment-24366645-20141118025139

We have no way of knowing an exact number. But from personal appearance I believe it is lower than other guerrilla bosses. If you would like to increase your chances of her appearing/dropping you can wait for her to spawn in Quintessence or Lorentz Labo, because these are higher level areas she might be easier to acquire there.

It's all speculation when it comes to rates really ^^;