Since today is the Conciliar / Wojtylan Great "Feast of Divine Mercy" ... as if that wasn't Good Friday through Easter already, and the Dimond Brothers reposted this great video ...
I have to wonder whether Sister Faustina was just mentally disturbed or whether there was a diabolical element to the false devotion ... an attempt to displace the Sacred Heart of Jesus, create presumption in God's mercy (in lieu of Confession), etc. God typically introduces new devotions to offset various imbalances, such as the Sacred Heart devotion to offset the Jansenist mentality. Since Vatican II, there's been no shortage of people who already believe (too much) in God's Mercy, at the expense of His Justice. So this devotion, having come when it did, actually adds fuel to a disorder rather than offsetting it.
I was reminded of the fiction character "Faust" (coincidence?), who sold his soul to the devil for knowledge, power ... and pleasure. Women tend to be more interested in fame, attention, and influence than in power, so that would be their equivalent.
There was that nun Magdalena de la Cruz who had made a similar deal in the 1500s.