With Solar 3.0 in Destiny 2, there are many Guardians playing with builds comprised of the various abilities, aspects, and Fragments available. However, keen-eyed Guardians have noticed that not all Fragments are available. Ember of Empyrean, Ember of Char, Ember of Ashes, and Ember of Wonder are currently unavailable, despite their listing in the Solar 3.0 Fragments. The other Fragments can be purchased from Ikora in The Tower, much like how Void 3.0 was handled when The Witch Queen was released.
In a confusing move, Bungie announced that it would be holding a competition to unlock the remaining Fragments. Once Guardians have completed 20 million Nightmare Containment community completions, the remaining Fragments will become available for purchase.
Note that each individual Guardian completion counts as one, so the more in each instance of the event, the better. At this time, Bungie has not made any further announcements regarding the progress of the challenge or if it can be tracked. Until it does, Guardians will need to hold tight.
Compounding matters is that some long-time players have access to the Fragments. This was an unintended bug that Bungie has opted not to resolve. If you're one of those lucky few, enjoy toying around with the Fragments. Hopefully, everyone will have access to them soon enough.
For more Destiny 2 goodies, check out Best SMGs in Destiny 2 on Pro Game Guides.