Eternal has several game currencies.
Shiftstone is used in Eternal's crafting system.
Gems may be used to buy anything that can bought with gold. Gems are purchased with money through the game's store. Some items can only be bought with gems, such as some premium upgrades, promotions, and cosmetics, though game content (regular-version card availability, game modes, and events) is never restricted to gems/cash only.
Influence can be earned by linking your eternal and twitch accounts and then streaming or watching streams on twitch. Streamers will additionally need the Waystone extension to be enabled.