Chthonic Key



Chthonic Keys are one of several Artifact currencies that can be found within the Underworld. They allow Zagreus to unlock additional upgrade choices at the Mirror of Night, as well as additional Infernal Arms.

Obtaining Chthonic Keys

 * Chthonic Keys can be received as a room clear reward, from Charon's shop, from the Fated List of Minor Prophecies, from the Wretched Broker, or from Fishing.
 * With the Fated Keys upgrade from the House Contractor, Chthonic Keys will also give Fated Authority or  Fated Persuasion (i.e. +1 Reroll) when collected from a room reward.

Using Chthonic keys

 * You can spend a total of 89 Chthonic Keys on permanent unlocks (65 at the Mirror of Night and 24 for Infernal Arms).
 * Resetting talent and refunding darkness from Mirror of Night requires 1 Chthonic Key for each reset.
 * Chthonic Keys can be used in trades with the Wretched Broker.
 * Several of the ranks from the Resource Director require spending Chthonic Keys to obtain them (100 Keys in total).
 * It costs 200 Chthonic Keys to buy the Chthonic Theme from the House Contractor (once available).

Additional Notes

 * Prior to the Welcome to Hell Update, "Chthonic Keys" had the functionality of Titan Blood, with "Skeleton Keys" instead used for unlocking talents and weapons.