The blood oath is said to have taken place in Etelkoz in the 9th century, under Upper Prince Elmos, before the hike in the Carpathian Basin. The author of Gesta, known as „Master P” and more commonly called „Anonymus,” told his story in his book. The description of the swearing-in ceremony reflects the political and social changes of Anonymus` lifetime. The growing power of the nobles and their need to codify their rights culminated with the edition of the Golden Bull of 1222. Several historians have concluded that anonymus` intention to write this agreement was to express social changes during his own period and to support the struggle for the rights of the nobility as a kind of historical justification. The aim of Magister P. (Anonymus) is to justify the rights and claims of the Hungarian nobility of the 13th century and to create a lineage that goes back to the conquest of all his friends and family. Although Anonymus points out that his works are based on written sources, he wanted to create a literary work in the style of his own time.  However, the terms of the pact would not prevent Dumbledore from defeating Grindelwald for good many years later in 1945. It is not known what the consequence of the breakdown of the pact should be and how they managed to circumvent it if they had actually succeeded in destroying the blood pact by then. Blood Pact Type Magical Contract Fixing Effect Creates a magical bond between two people by sharing blood [source] A blood pact (unknown incantation) is a kind of binding magic agreement between two parties who share their blood. It could be done by parties that cut off their hands with their magic wands and intersmail them and take the oath they desire. In this way, two drops of burning blood would come out of the palms of their hands and mix into one. Then a vial has to take shape around it, surrounding the drop, which means that the deal has been concluded.
Newt gives Dumbledore his pacs of blood to Hogwarts With my blood, I swear my life to the judge and his jury to the end, in the pain of torture and death. Albus Dumbledore and Gellert Grindelwald entered into a blood pact in which they vowed never to fight each other – probably to ensure that, in their great will to ignite the revolution between magic aggregations and non-magic aggregations, they should finally predominate first to mark an era of sovereignty over them. Albus and Gellert direct them in the same way as unique leaders, without the magician being smaller or taller than the other.   Until 1927, Grindelwald still had the vial of this pact to protect him from Dumbledore, so that Dumbledore could never attack him directly.  However, the pact worked both ways and was therefore a double-edged sword, for while protecting Grindelwald from Dumbledore, it itself prevented Grindelwald from personally eliminating Dumbledore, the greatest threat to his cause.