Destiny 2’s latest season adds a new deckbuilding element that allows you to gain buffs when running Season of the Witch activities. These take the form of Minor Arcana and Major Arcana. But to acquire these buffs, you must first farm Opaque Cards. So, here's a guide on how to get Opaque Cards and how to unlock their abilities.
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How to Get Opaque Cards
To earn Opaque cards, complete Season of the Witch activities such as Altars of Summoning and Savathun’s Spire. When you end one of these activities, watch your loot feed and see if you earned an Opaque Card.
Other sources can provide you with Opaque Cards, too. Ritual playlists such as Crucible and Vanguard Strikes can also drop Opaque cards, but these may only unlock Minor Arcana from the Lectern of Divination.

Another way to increase your collection of Opaque cards is to rank up with the Ritual Table in the Athenaeum. Four cards are available in the rewards tree, and XP for the table can be earned by completing seasonal activities and Ritual Table bounties. Be aware that Rank 7 through Rank 16 rewards only provide Minor Arcana cards.
Additionally, there is a bonus card hidden behind a tree in the Athenaeum, and it's possible that there are more hidden cards across the system.
How to Upgrade Opaque Cards to Major and Minor Arcana
Once you have an Opaque Card, you can take it to the Lectern of Divination in the Athenaeum, which you can access from the HELM. Head down the back stairs and past Crow, then jump through the large Hive portal to reach the area — step three of the Toil and Trouble quest allows access to the Athenaeum. Here, you can convert Opaque Cards into a Major Arcana or Minor Arcana.
Minor Arcana in Destiny 2
Minor Arcana will provide buffs that affect your progression during the season. These can include the usual upgrade, such as weekly Deepsight weapons and additional items from using Witch Keys at the end of activities. These cards automatically take effect when they are unlocked and don’t require any further steps.
Major Arcana in Destiny 2
After unlocking a Major Arcana card, you will still need to complete an associated mini-quest for each card to transform it into a buff. Then, the card gets added to your Deck of Whispers. An example of a Major Arcana buff is the Harbinger card, which gives final blows a chance to create an explosion that damages enemies.
The mini-quest can task you with participating in Altars of Sorrow, defeating enemies in Altars of Summoning, or even completing public events to collect Insight. (Since you earn Insight from participating in the mini-quest’s respective task, you can’t really farm Insight.)
Keep in mind, your Deck of Whispers must contain at least five cards to draw from it in the Altars of Summoning and Savathun’s Spire activities. Otherwise, you won’t receive any bonuses or buffs during those seasonal activities. To complete the entire set, you will have to acquire a total of 12 Major Arcana and 22 Minor Arcana.