Hero Siege Mysterious Key Quest - Full Steps

The Mysterious Key quest spans the whole game — it starts in the first town and finishes at a boss in Act 7.

What are the Mysterious Key quest steps?

Step	Where	What to do
1	1-0 Town of Inoya	Talk to Yogvan Beerdrinka
2	Anywhere	Mine 125 Copper Ore — on Normal difficulty
3	7-5 Subconscious Mind → The Void Dungeon	Kill Mevius to get the Mysterious Key
4	4-0 Dhorn Farum	Open the door in the top right corner of the town
5	4-0 Dhorn Farum	Talk to Örre

Why does the copper ore step specify Normal difficulty?

Because it does — the requirement is 125 Copper Ore mined in Normal Difficulty specifically. This is unusual: most collection steps do not care what difficulty you are on.

The practical consequence is that if you have already progressed past Normal, you may need to go back for this step rather than gathering it wherever you happen to be farming.

Where exactly is Mevius?

7-5 Subconscious Mind → The Void Dungeon.

Mevius is worth knowing regardless of this quest: he is the boss that gates every difficulty tier. Nightmare requires killing him on Normal, Hell requires him on Nightmare, and Hell 2 and Hell 3 each require him again on the tier below.

So a trip to The Void Dungeon serves both the Mysterious Key and whatever difficulty unlock you are working on.

What does the door at Dhorn Farum open?

Not documented in the material behind this page. The quest step is specific about where — top right corner of 4-0 Dhorn Farum — and about talking to Örre afterwards, but the reward beyond that is not stated.

Örre is the questgiver for several chains including Seething Souls and the Awesome Ring, so the door plausibly opens further questing rather than a single item.

The Hurnir location guide covers the same Dhorn Farum quest area, and the quest overview places both chains in progression order. The Awesome Ring quest is the documented long-form ring chain associated with this part of the game, but it should not be treated as proof of what the mysterious door contains.

Next step

Do the copper ore while you are still on Normal — going back for it later is the one part of this chain that wastes real time.