The Fire Cairns are key in Infernium. When you die, you will be teleported to The Purgatory. There, when you interact with the black goo in the center, you will be teleported to the last Fire Cairn you activated.
To activate a Fire Cairn, just approach it and hold the interact button. You will see some flames start to appear. Keep holding the button until you hear an explosion. If you release the button now, there should still be flames over the black sand.
Usually you will have to search the levels a little bit to find each level's Fire Cairn. Some of them are a little bit hidden but each level except The Sun, The Beach, Purgatory and Twin Fountains have a Fire Cairn on it. Please read the guide to know each Fire Cairn location.
Permadeath[edit | edit source]
If you are in the permadeath state you won't be able to reespawn back to the Fire Cairns. If you try to continue a game while on permadeath you will be teleported to the Purgatory instead of the Fire Cairn. But don't worry, there are ways to avoid permadeath.