This curse was used by Lord Voldemort in 1998 to breach the Hogwarts protection set up by Molly Weasley, Filius Flitwick and Horace Slughorn.
The incantation is unknown but the spell must take a lot of power to cast, as the Elder Wand cracked down the middle.
Protection
In 1998 the Order of the Phoenix attempted to protect Hogwarts with protective spells(Fianto Duri, Repello Inimigotum, Protego Maxima), 3 very powerful spells merged together to form the Hogwarts protection, these spells made Death Eater hard like rock and then shatter, after sometime Voldemort used the Shield Penetration Curse to destroy the barrier between Him and Hogwarts, the results of this spell were catastrophic.