To my understanding you can buy bundles from other players, which is the most direct way of turning forum gold into cards.
The most common way of generating cards from forum gold is buying the ”Play-a-Friend” quest from other players of the same region. I do believe this quest can be completed, by one player, up to a maximum of 5 times per day. Allowing a player to make up to 400 hearthstone gold each day, ontop of the gold earned from regular quests.
This post was edited by nevah on Dec 31 2018 08:48am