these are all the timed exclusive stuff on the PS platforms.
http://www.playstation.com/en-ca/games/destiny-ps4/exclusive-content/
Destiny Expansion I:
The Dark Below
Expand your Destiny adventure with a wealth of weapons, armor, and gear earned in new story missions, three new competitive multiplayer arenas, and a new cooperative Strike and Raid. Beneath the surface of the Moon, a long-forgotten enemy wakes. Survive the true depths of the Hellmouth, and stop its dark army from invading Earth.
The Dark Below also includes these PlayStation exclusives*:
PRE-ORDER EXPANSION I: THE DARK BELOW
Strike
The Undying Mind
An ancient Mind, feared by the Vex themselves, hides among the channels of the Black Garden. Find this machine and end its existence.
- An exclusive three-player cooperative Strike that can be played with friends, or matchmade.
- When The Undying Mind is threatened, its ancient creators step through time portals to defend it, ensuring that it will continue to thrive, until the Vex once again control the Black Garden.
Exotic Shotgun
The 4th Horseman
The four-barrel, five shot, Arc damage, full-auto shotgun features a faster rate of fire than any other shotgun you can get your hands on. Hang on tight, pull the trigger, and let the Horseman ride.
- Final Round
The last round in a magazine deals bonus damage.
- Return to Sender
Kills with this weapon grant bonus ammo, directly to the magazine.
Strike
Dust Palace
Deep in the Dust Palace, a skyscraper buried deeply in the sands of Mars, the Cabal have captured a human Golden Age artificial intelligence construct that still hums with life. Fight through the Cabal army. Defeat the Psion Flayers. Reclaim the construct.
- An exclusive three-player cooperative Strike that can be played with friends, or matchmade.
- Track a Cabal extraction team through the husks of an ancient human skyscraper buried in the shifting dunes of Mars and face a new enemy, the Psion Flayers.