Season of Arrivals introduced a resource in Destiny 2, the Exotic Cipher, that has become even more relevant since Beyond Light. You can use Exotic Ciphers to purchase Exotic weapons that you don’t own, and had their quests moved out of the game with the great Content Vaulting of 2020, by visiting the Exotic Archive in the Tower.
If you visit the Exotic Archive, you will find various options for older DLCs. Clicking on them will allow you to purchase Exotics you are missing if you have the materials to purchase it. One of the required materials is an Exotic Cipher.
There are two sources for Exotic Ciphers in Destiny 2. First, the Season Pass. Ranking up the Season Pass will earn you an Exotic Cipher at Rank 55.
You can also get them by completing a quest for Xur every week. You can only hold one at a time, however, so if you really want to take advantage of these quests, you will need to get them finished each weekend before he leaves with the weekly reset on Tuesdays, then get them spent before he comes back again.
This is easier said than done, as the weapons also require an Ascendant Shard to be able to buy them, and these are tough to get and require a lot of grinding no matter how you do it.
Due to all the work involved, we would suggest being very careful about grabbing weapons this way, but if you want some advice on what to get, we would suggest the Eriana’s Vow and the Anarchy if you don’t have them. Thorn is also a strong prospect, as is the Ace of Spades, and the Izanagi’s Burden.
The final source for Exotic Ciphers is as a reward for completing certain Triumphs. These are far-reaching challenges that can often take an entire Season to complete.