How to get Oxygen SR3 in Destiny 2's Season of the Drifter

A Dragonfly Scout Rifle might initially pass off as merely ho-hum for a Destiny 2 Pinnacle weapon, but Oxygen SR3 puts a twist on it. Its unique perk, Meganeura, buffs Dragonfly’s climactic boom if you land successive precision hits (headshots) before the kill. Think of it as a conclusive “and stay down!” for elite PvE enemies. Though it’ll struggle for sturdy footing in the peek-a-boo playstyle of the Crucible, the Oxygen is a fun companion for tormenting mobs in overworld activities such as Public Events or Lost Sectors.

Get the “Redeployment” Pursuit from Zavala in the Tower

Nothing complicated here. Keep the Pursuit in your inventory and don’t touch it until you need to hand it back to Zavala.

Complete the “The Best Offense” Vanguard Triumph: land 1,000 precision final blows, generate 500 Orbs, and complete Strikes and Nightfalls

Precision hits generate yellow damage numbers, typically on a headshot or other vulnerable spot (glowing stomach orbs for the Vex). You’ll need to make sure your foes fall on a precision hit, so equip whatever weaponry you’re most comfortable with—hand cannons or scout rifles are ideal candidates—and favor Strikes that frequently present clumped enemy groups such as Inverted Spire or Savathun’s Song. 

Use Masterworked weapons in conjunction with generous Super usage to keep Orbs flowing. Something to note is that the game seems to track the numbers of times that the 'player has generated X orb(s) of light' message appears on screen, rather than the total number of orbs. This is a bug which will be fixed in time, but for now you're best off using roaming supers rather than one-and-done variants (eg Nova Bombs) so you can space out Orb generation.

Each completed Strike increases its associated criteria by 1% while each Nightfall provides a 5% bump, so if toiling through 100 Strikes seems too daunting, you can always mix in a few Nightfalls for a small boost to efficiency. Given that you're not trying to hit a high score, don't forget you can use the Nightfall Challenge card (available from the weekend vendor Xur), to lower the difficulty and add beneficial modifiers such as Heavyweight and the elemental singe of your choice.