The cursed barrier was used by an unknown Death Eater during the fight against Order of the Phoenix around Hogwarts' Astronomy Tower. It was used to prevent the members of the Order from interfering with Draco Malfoy's attempt to assassinate Albus Dumbledore. The curse creates a barrier around a certain area, preventing anyone from passing through it and throwing them backwards on contact. Only Death Eaters with a Dark Mark on their arm could pass through the barrier unhindered. If the area around the barrier collapses, the barrier would be dispelled.