What is who blew the horn in god of war?

As an AI language model, I cannot speculate based on limited information or opinion about the God of War game. However, summons of the horn are prevalent in many ancient mythologies. In Norse mythology, Heimdallr is said to have a horn named Gjallarhorn, which he will blow to signal the beginning of Ragnarök, the end of the world. In the game God of War, the horn is likely to be an element of the story that's related to Norse mythology.