To unlock the Realm of Fire / Muspelheim in God of War, you need to find 4 Muspelheim Ciphers. This will complete the Realm of Fire language disc and allows you to travel to the new realm.
These Realm of Fire Ciphers are locked away in special chests with a mask as a lock. You can find more than 4 of these chests around the world but the ones shown in the video can be unlocked early on.
1 Cliffs of the Raven 00:03
2 Alfheim 00:58
3 Forgotten Caverns 01:26
4 Forgotten Caverns 02:05
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