After the Destiny 2: Lightfall campaign, you're given basic Strand abilities, but you'll need to purchase grenades, Aspects, and Fragments from the Pouka Pond in Hall of Heroes on Neomuna. Strand Meditations are currency stored in your inventory that let you purchase additional abilities. Once you've unlocked the full suite of abilities, you'll then be able to start a quest to obtain a new Exotic sidearm, Final Warning. Here's what to expect.

You'll earn 300 Strand Meditations by speaking to Nimbus if you complete the Legendary campaign, and the Pouka Pond will give you 500 to start unlocking options.

The grenade section has the Threadling grenade, Shackle grenade, and Grapple; each of those abilities costs 50 Strand Meditations. The two Aspects cost 150 Strand Meditations each, and each of the 14 Fragments costs 200 Strand Meditations. Unlocking all Strand abilities on a single class will help customize your subclass, but it'll also unlock The Final Strand Exotic quest.