The Taken King has added a bevy of features to Destiny (opens in new tab), and Bungie has hidden several Exotic weapons in timed Heroic missions. When Lost to Light is active as the Daily Heroic, you can pick up Black Spindle - an Exotic sniper rifle, which is the spiritual successor to Black Hammer, a popular weapon from Destiny's year one. Here's how to get it:
Fire up the Daily Heroic Story mission, when Lost to Light is in rotation. (Reddit users are saying (opens in new tab) that if you try to do Lost to Light on normal difficulty, the event which triggers the hidden mission won't occur.) Rush through the level as fast as possible and, upon reaching a door that requires three relics to open, turn around and head instead for the Fallen Ketch - "Ketch," if you're unfamiliar, is what Fallen call their largest ships. Ghost will mention that he's picking up Fallen distress beacons, and you'll be transported up and into the Ketch. You now have 10 minutes to kill every last Taken enemy. Our advice is to take a fireteam, as you'll struggle solo. Success looks something like this:
Looking for more secret stuff in Destiny? Here's how to get the elusive Sleeper Simulant (opens in new tab). And our guide to grabbing No Time To Explain (opens in new tab), the Exotic pulse rifle. Happy hunting.