Update: In response to complaints about drop rates, Bungie has released an update that "drastically" increases it, and said that it will continue to monitor for possible further tweaks.
We’ve deployed a fix that will drastically increase Cipher Decoder drop rates from completing activities throughout the game. We’ll continue to monitor the situation to determine if further fixes are necessary.Players may need to restart their game to receive the update.October 8, 2020
The hand that giveth also taketh away though, as Bungie has also said that it is fixing the exploit which enabled players to farm various materials, including Cipher Decoders, from the Spire of Stars raid lair boss checkpoint. I'll leave the video explanation of that in the original story below in case you're curious.
Destiny 2's seasonal Festival of the Lost is now in full swing, and so far the spookiest thing about it has been the stingy drop rate of Cipher Decoders. These are a new consumable that you'll need to complete the Triumphs needed to unlock the mummy-themed cosmetics which Eva Levante has in the Tower. The drop rate is so paltry that Bungie community manager Cozmo posted in a related Reddit thread that: "We're currently investigating the drop rate of Cipher Decoders."
Assuming you don't want to wait to see how that investigation pans out, the guide below will explain how to stock up on Cipher Decoders. Warning: it's more trick than treat. But first...
What is a Cipher Decoder?
A Cipher Decoder is a legendary item drop used to open the caches at the end of the Haunted Forest activity. You can spend up to five Deciphers in one run. This means you have five chances per run at obtaining a god roll legendary Horror Story or Braytech Werewolf. Note that 1) these are both reskins of 450 RPM auto rifles, and as such are seen as inferior to the 600 RPMs (such as The Summoner and Gnawing Hunger) that dominate the meta in PvE and PvP. 2) If you played the Infinite Forest in previous years there's a good chance you can grab the curated roll of these guns from your collection, and it will come out with a 1360 power cap.
So if you don't care about Eva's cosmetics, you could skip the event altogether. But if you're still here, let's get our grind on.
How do I farm Cipher Decoders?
Cipher Decoders are legendary world drops that are sometimes rewarded for the completion of activities. That means you won’t be able to farm them by completing the Haunted Forest itself.
You can, however, find them in nearly all of the other activities in the Destiny 2 universe. This means the simplest and most efficient way is to grind the fastest events possible. As time and difficulty are the most influential factors when it comes to efficient grinding, your best bet are low tier Nightmare Hunts and the Daily Heroic Story Missions.
In the Heroic Story Missions, keep an eye out for:
Ice and Shadow, Gateway, Riptide, A Deadly Trial, and Unbroken
1AU, Last Call, The Machinist, and Nothing Left to Say
Alternatively, you can also farm patrols which are even quicker to complete, if a little brain numbing. All you need to do is head to a destination where you know easy patrols spawn. The 'kill enemies' patrol is obviously the quickest, and that can usually be found at the Artifact's Edge on Nessus and Thieves' Landing on the Tangled Shore. Some players think the Moon is the best zone overall due to the easy Toland patrols.
Isn't there a way to cheese it?
You are in luck, my unscrupulous friend, but it will require a specific checkpoint from the Spire of Stars raid lair. And it'll also involve some boring shuttling back and forth from orbit with at least one friend. YouTuber Aztecross was able to get 10 Ciphers in 20 minutes using the cheese, which he explains how to do in the video below. In order to acquire a boss checkpoint you can ask (nicely) in the raid channel of the Destiny 2 PC LFG Discord channel. This method is definitely a glitch (there was a similar one for the Prophecy dungeon when it launched) and therefore I would expect it to be patched out eventually.
How bad is the drop rate right now?
A sleuth on Reddit revealed that the current drop rate for Cipher Decoders is less than 1 in 4 when it comes to activity completions. When you consider that the most efficient way to use Cipher Decoders is in sets of five, that means you need roughly 20 non-Haunted Forest event completions between each run. Which, let's be real, feels tedious when the main rewards on offer are some so-so autos.
We'll update this post if Bungie ups the drop rate before the Festival ends on 3 November, but in the meantime you might consider the glorious bounty that is double-reward Nightfalls instead. It's live this week and much more generous.