Destiny 2 got a wealth of new content with the Season of the Chosen, a new seasonal update focusing on the Cabal and the evil Empress Caiatal who is trying to consolidate power in the solar system. The season mainly revolves around the new Battlegrounds and the special ritual item, the Hammer of Proving. That said, don't expect to be grinding nothing but Battlegrounds while the season lasts, since you'll need to spend time in other activities as well to earn Cabal Gold.
What is Cabal Gold?
Cabal Gold is a new seasonal currency introduced specifically for the Season of the Chosen. You'll only start earning Cabal Gold after you unlocked your own Hammer of Proving by completing the two Battlegrounds introductory missions, called the Challenger's Proving, as well as the Umbral Engrams introductory mission called Decrypting the Darkness. The Hammer of Proving is used to decrypt Umbral Engrams and smash chests at the end of Battleground matches - you can read more about how to unlock the hammer and what it does here.
Cabal Gold is tied to the hammer because you'll be using it to upgrade the fancy weapon. Cabal Gold is mostly spent on Etched Challenger Medals which cost 14 pieces of the new currency, and allow the Hammer of Proving to smash more caches at the end of Battlegrounds. Each smashed cache grants you one Hammer Charge which is the consumed during the decryption of Umbral Engrams, meaning the more Medals you have, the more Charges you get and the more Engrams you decrypt. Umbral Engrams contain the powerful new seasonal equipment, so increasing your decryption rate will speed up progress.
How to earn Cabal Gold?
Despite being the seasonal currency, Cabal Gold is not earned from the seasonal activity, Battlegrounds. You're going to have to run some of those other activities you usually do in order to upgrade your hammer. Activities paying out Cabal Gold include Strikes, Dungeons, Crucible matches, Gambit matches and public events, with cabal Gold payouts depending on the type of activity and your performance during it.
Players have noted that Strikes pay out the most Cabal Gold, averaging at 14 per Strike, already earning you an Etched Challenger Medal. Dungeons and Raids are affected by a bug that prevents them from paying out Cabal Gold, so we do not know how effective a source they are for the new seasonal currency. PvP matches pay out less than Strikes do, with many players earning around 8 pieces of Cabal Gold per match. This does vary based on how well you perform during the match, however.
Is Cabal Gold capped?
Yes, actually. Not only is there a limit to how much Cabal Gold you can have at any given time, this cap is linked to the upgrade status of your Hammer of Proving. With an un-upgraded Hammer of Proving, you'll only be able to carry 42 pieces of Cabal Gold at any given time, meaning any Cabal Gold earned in excess of that will just disappear. Make sure to spend the Cabal Gold as you earn it, since upgrading your Hammer will also buff out the capacity too.
Will more activities pay out Cabal Gold later?
Yes, we know for a fact that additional activities and challenges will be added to the Season of Proving at various points throughout February that will pay out Cabal Gold. While they don't pay out Cabal Gold, Battlegrounds are also getting expanded - we currently have access to just 2, with another 2 to be unlocked later this month.