Update: We have gotten some further info from a fellow player who said these can drop randomly in the world, from Crucible match, Nightfalls, Heroic Public Events, Raids, and Gambit. We haven’t confirmed yet but thought his information could be useful to people.
Original Article: Season of Arrivals has brought a new resource in Destiny 2, the Exotic Cipher. The Exotic Cipher seems to have a couple of uses, but at the moment, we have only been able to find a singular source, but we assume there are more, as we will explain in a moment.
If you visit Rahool, you will notice that he can now sell you an Exotic weapon, if you have the materials to purchase it. One of the required materials is an Exotic Cipher. The only source of Exotic Ciphers we have discovered in the game is from the Season Pass.
It seems we will be able to earn more because of a line from the patch notes for the most recent update. Under the “Vendor” section, it reads, “Added the ability to use an Exotic Cipher to purchase a second Fated engram from Xur each week.”
While it may be possible that we only get a single Exotic Cipher from the Season Pass, it seems unlikely that this functionality would have been added to Xur if we were unable to get any more Exotic Ciphers at all.
We will hunt through the game to find Exotic Ciphers sources and update this guide when we track them down. While it seems unlikely anyone will be able to get to Tier 55 too fast, it might be worth holding onto any extra Exotic Ciphers you manage to get, just to be sure you are using them on the exact items you want, in case they are quite rare.