What manner of entities?
How is it useless? Unless it was just a coincidence that they left or they left because it was my will for them to leave.
The LBRP functions in a similar way to making yourself seem large against wild animals.
You stomp, you roar, you look big and threatening, and most bottom-feeders and random parasites will simply screw off. Unless, that is, they’re starving.
What the LBRP actually does is similar to Skyrim’s “Fus Ro Dah”- it blows things away… but it doesn’t actually hurt them.
You can send an entity to the other side of the multiverse if you’re skilled enough, but if it knows how to maneuver those lands it could be back, in time.
Most magicians cannot throw things out of this universe through banishing rituals.
And sometimes, if a creature is compelled to attack you, is starving, or otherwise seeks your blood enough that a little defense won’t stop it from coming after you, then you need to either roll over and submit, or kill it.
The LBRP can, when dealing with true opponents, only buy you time- that is, if we’re operating under the assumption that the opponent is simply stronger than the beings you call upon.
Then it’s like hiding behind a door only to have it smashed down.
And, being honest, if the being after your blood is capable of brushing off the archangels, and the LBRP is still something you use to deal with hostile beings, then you’re likely screwed anyway.