Last year when I was in Walsingham for three months, I met many Catholic charismatics. One of the things I noticed was that they were using regularly the long version of the "Prayer Against Satan and Rebellious Angels Published by Order of H. H. Pope Leo XIII.
I mentioned to some of those I met that this prayer was not to be used in meetings. I was rebuked. I also came to realize this prayer is not to be used except by priests and not by the laity.
This is a warning via an excellent priest who confirmed my suspicions that this prayer is dangerous if used incorrectly.
What do I mean?
Demons and especially Satan himself, a person albeit spirit, is highly intelligent, more than all of us.
They literally watch us over the years, learn our weaknesses and prey upon those.
They cannot read our minds but these spirits can watch, wait and tempt.
When we say prayers against them and we are not holy, are not fasting, are not disciplined or AND THIS IS THE MOST IMPORTANT POINT, not under the diocesan authority of the bishop with regard to exorcisms, we are actually calling down these beings into our own homes and persons.
I know this from this wise priest and from others who have had personal experience of attempting to address demons without the authority of the Church.
What I have seen is this. When those who use this prayer continue to do so, they fall into deceit and heresy.
Period.
Weakness leads to disobedience and ignorance leads to disobedience.
Disobedience leads to heresy and the loss of one's soul.
Please do not use this prayer and correct those who are using it.