Godtuner

Uses
When defeating a boss that is required to unlock a pantheon, it will appear on screen beneath the health bar and blink.

How to Acquire
It is dropped by the Godseeker automatically when they are freed from their coffin at the Junk Pit by using a Simple Key.

Trivia

 * There are 5 notches in the Godtuner section of the Inventory. Each notch seems to correspond to each pantheon in Godhome. Each notch will change appearance according to the completion status of the corresponding pantheon (which includes the bindings used).