|Muggles' Guide to Harry Potter - Magic|
|Features||Causes confusion in the subject|
|First Appearance||Harry Potter and the Prisoner of Azkaban|
The Confundus charm makes the subject confused. It is fairly advanced magic and is cast by means of the incantation "Confundo." The Confundus charm can apparently also be cast silently.
In Harry Potter and the Prisoner of Azkaban, Severus Snape knows that his story of what happened in the Shrieking Shack will differ radically from Harry's, so he claims that Harry was obviously suffering under the effects of a Confundus charm.
Professor Moody, in Harry Potter and the Goblet of Fire, suggests that the Goblet may have been Confunded to believe that there were four schools. While it is never explicitly stated that the Confundus charm was used, no other spell has been mentioned that would have similar effects. This is an indication that the Confundus charm may also work on inanimate objects that have been magically granted some level of reasoning ability, such as the Goblet and the Sorting Hat.
We later see that Snape may have put Mundungus Fletcher under the Confundus charm to secretly give him the idea of having multiple Harrys flying to multiple safe-houses.
Finally, in the Epilogue, Ron admits to having Confunded his driving examiner into overlooking an error (checking a wing mirror) that Ron considers trivial.
Cormac McLaggen's response to this charm would indicate that there are physical as well as mental effects; McLaggen, some time after he is Confunded, has trouble navigating stairs.
As seems to be the case with many other spells, there would appear to be a substantial mental component to this charm. The effects on McLaggen seem to be diverse and diffuse; however, Snape's discussion with Fudge, and Harry's using the charm to achieve a specific goal (convincing the guard that he has already been probed), suggests that the Confundus charm can, with the appropriate mental imagery imposed, cause the subject to believe something specific, other than what has happened.
Some characters, apparently, are more susceptible to this charm than others. We are told that Dawlish seems to be easily Confunded. We suspect that this probably relies on the same sort of mental control mechanism that underlies both the attraction of the Veela, and the Imperius curse. We would expect, in that case, that it would be harder to Confund Harry, as he has shown ability to throw off the Imperius curse completely. Ron, however, with his demonstrated susceptibility to both Veela and the Imperius curse, likely would be very easy to Confund.