When demons showed up, St. Faustina knew what to do.

Turn to any page of St. Faustina's Diary, and you'll find spiritual gems. Like this one:My daughter, have fear of nothing; I am always with you. All your adversaries will harm you only to the degree that I permit them to do so. (431)

Saint Faustina prayed the Rosary every day. One time, she wrote:… [One time] I saw many demons. One of these tried to vex me; taking the form of a cat, he kept throwing himself onto my bed and on my feet, and he was quite heavy, as if [weighing] a ton. I kept praying the rosary all the while, and toward dawn these beings vanished, and I was able to get some sleep. (412)