Surtr's Hidden Trials - God of War

Completing Surtr's Hidden Trials in God of War. The Impossible Trials of Muspelheim, also known as Surtr's Hidden Trials, are trials that are unlocked once you have completed all of the Normal and Hard trials in Muspelheim and defeated the Valkyrie at the top of the mountain. These are the only trials you can replay in Muspelheim. There are 5 trials with one in each of the first 5 arenas and they can be done in any order. Completing one of the trials earns you a key. You'll need 3 keys to unlock the sixth trial at the top of the mountain called Surtr's Hidden Trials which needs to be completed to get the Fire and Brimstone trophy along with the Crest of Surtr (note: don't bother getting more than 3 keys at once because you'll lose all of the keys you've obtained once you complete Surtr's Hidden Trials)