In need of new weapons and more upgrades? You need one of the important Artifact currencies in Supergiant Games’ Hades called Chthonic Keys. These keys are used to unlock specific upgrades in the game. These are what Chthonic Keys can unlock:
- Unlock each of the Infernal Arms (a total of 24 Chthonic Keys will be used to unlock them all).
- Unlock upgrades at the Mirror of the Night.
- Resetting upgrades from the Mirror of the Night and refunding all the Darkness used (requires one Chthonic Key for each reset).
- Used for trades with the Wretched Broker.
- Purchase the Chthonic Theme for 200 Chthonic Keys from the House Contractor.
- Purchase ranks from the Resource Director.
- If the Chthonic Keys, Fated upgrade has been purchased from the House Contractor, obtaining a Chthonic Key as a chamber reward will also grant +1 Fated Authority or +1 Fated Persuasion.
As you can see in the uses of Chthonic Keys mentioned above, these keys are essential, especially early on in the game. They unlock items that help conquer chambers and bosses in the Underworld, so Zagreus can finally escape.
Here are ways to obtain Chthonic Keys:
The most common and most reliable way of obtaining Chthonic Keys is through rewards for completing chambers. Fortunately, it is easy to know what the reward of each chamber is from the icon on the door.
Fishes in Asphodel can be exchanged for Chthonic Keys. After every run, you should exchange caught fish with the Head Chef in the kitchen of the House of Hades. The fish that can be caught in Asphodel are Slavug (Common, exchanged for 1 Chthonic Key), Chrustacean (Rare, exchanged for 3 Chthonic Keys), and Flameater (Legendary, exchanged for 5 Chthonic Keys).
This is not a reliable source of Chthonic Keys as fishing spots are not guaranteed to appear in Asphodel (unless forced by a boon). Additionally, if a fishing spot has already spawned on Tartarus, the chances of it appearing in Asphodel are smaller. However, if you do catch fish in Asphodel, remember to exchange them with the Head Chef after every run, as they will not carry over on your next run.
It is worth mentioning that obtaining Poseidon’s Huge Catch Boon increases the chance of a fishing spot appearing in each chamber.
During your runs, Chthonic Keys can occasionally be purchased for a few Obols from Charon’s Shop. After your runs, on the other hand, you can buy Chthonic Keys from the Wretched Broker if you have a few Gemstones to spare. Be sure to check with the Wretched Broker for limited-time offers regularly.
After purchasing it from the House Contractor, the Fated List of Minor Prophecies will reward you with Chthonic Keys for fulfilling prophecies like Chthonic Colleagues (meet characters from the Underworld) for 10 Chthonic Keys. Regularly check the Fated List to see if you are close to fulfilling these prophecies.
We could not emphasize enough Chthonic Keys are helpful early in the game as they can help Zagreus become stronger and faster because of the upgrades and weapons. So, every time you see that key on the chamber door, make sure to go through it!