She is older than any written language. She is so ancient that her true name is unknown even to her. She is cursed to turn any living flesh she gazes upon into gold. Every single gold coin, statue, icon, holy symbol, and trinket originated with her gaze. She is the Mother of All Gold. It’s creator. And she is cursed to live forever untill some brave (or foolish) soul slays her and the curse is passed onto that poor sod.

What happens a party of adventurers encounter the Golden Eyed Medusa? She will not tell them of her curse. She will not fight back. She will let them kill her and whoever lands the death blow either blade or spell is the new bearer of the curse.

What happens next? Every bit of gold that was created by her (i.e. all of it) reverts back to original form basically meat and throwing most economies into total chaos.

What happens to the cursed character?
First, the character has petrifying gaze of a Medusa but instead of turning targets to stone. It turns them into gold. The gaze only affects living organisms. However, the character cannot control when the ability triggers. And there is nothing the character can do to prevent it.
Second, the character is nearly immortal and cannot die of natural causes. Only by the violent acts of another. And whoever kills the character gains the curse.
Third, the character can only gain sustenance by eating gold. The character cannot starve to death if they do not eat but they will become emaciated and suffer incredible hunger pangs. The gold tastes like what it originally was.
Fourth, the character poops gold. See above. And yes.

What else happens? Player characters at first will think this is a cash cow. Unfortunately, as soon as they show up in a civilized area with gold, they will be met with anger and suspicion. Because, yes, they did cause everyone’s gold to disappear. They will be the target of every king, warlord, criminal, wizard and dragon in the world. Enjoy that. In some places, gold might be totally valueless now. Who knows that’s up to the GM.