Spectral Pages are a new, temporary form of currency during the Festival of the Lost event in Destiny 2. These pages are the first step of the process to playing the new activity in the event called Haunted Sectors. They are used to eventually complete The Book of the Forgotten that's located in the Tower.
Before the Pages
Before you start collecting Spectral Pages, make sure that your Guardian is wearing a Festival Mask. You can only obtain Spectral Pages while wearing a mask. If you don't already have one, you can buy one from Eva Levante in the Tower. She is selling Master Rahool masks for 100 Glimmer.
Next, here are all the ways you can get Spectral Pages.
One of the best ways to collect Spectral Pages is by playing in the Vanguard Strikes playlist. After completing a Strike, while wearing a mask, you will be rewarded with 5 Spectral Pages. So, after each Strike you complete, you will get five more pages. This process is very easily repeatable and will reward you with a lot of pages.
The Nightfall is still under Vanguard Operations which means completing the Nightfall will also reward you with 5 Spectral Pages no matter the difficulty level. Luckily, this week's Nightfall is a quick one.
Related: Destiny 2 Weekly Reset Update
Crucible matches are another great way to get more Spectral Pages. After completing a Crucible match, you will be rewarded 3 Spectral Pages. This may be less than Strikes, but Crucible matches are often a lot quicker to complete. Any of the Crucible game modes will give you the same outcome in terms of Spectral Pages.
Gambit, just like Crucible, will also give you 3 Spectral Pages. Gambit matches can sometimes take a little longer than other activities, but if you like the mixed PvE and PvP game style then this will be your go-to for more Spectral Pages.
For more Destiny 2 content, check out How to Start Haunted Sectors in Destiny 2 on Pro Game Guides!