What is gold for in Game of Thrones: Dragonfire?

Gold is the only permanent currency in the game: it never resets between reigns. It's your most valuable capital.

What you spend it on:

• Opening Hatchery chests (an alternative to Dragonbone / Dragonglass / Dragonfire Keys)
• Buying at the Market: basic resources, relics, Cores
• Speeding up or unlocking certain purchases at the Hatchery

Because it's permanent, gold put into relics, Cores or keys is a definitive gain for your dragons. Trading gold for basic resources (which do reset) is a comfort purchase for the moment.

The golden rule, so to speak: spend your gold on what's permanent.