Bungie said there would be more secrets and one has just been disovered by some diligent players. Through what appears to be sheer luck a group of players discovered the secret door in the King's Fall raid area with the large pistons that can launch you for miles if you're hit.

Like many of Destiny's puzzles opeing the door requires that a set of switches get activated in a specific order. The exact order of which was unknown until another group of players came accross the first groups findings and tried to replicate it. One of the members of this second gorup was longtime Destiny Youtuber Planet Destiny who recorded the process in detail.

The room itself contains a relic and a some jump jets that allow the you to dunk the relic into a central statue. After the relic has been dunked a certain amount of times, all the players in the raid receive the overcharged buff. Whether that's the only secret the room holds has not been confirmed yet, so keep your eyes peeled on the destiny subreddit and offical Bungie forums for the latest as it's released.