Could use any help unlocking legendary gear amor helmets assassinations as well
Fastest way to complete your collections is to spam Arena/Warzone with RP boosts, open bronze & silver packs first to complete your common/uncommon/rare collections so you won’t be wasting points on gold packs only to get low tier items.
Also right now there are greatest hits customizer packs, grinding for those give you a high chance at rarer gear
The most effective way to unlock the Legendary items that are obtainable from the Gold Packs is to focus on efficient req point spending and collecting. When it comes to spending, it’s definitely preferable if you focus on unlocking all Uncommon and Rare permanent cards obtainable from Gold Packs from the cheaper Silver Packs which gives permanent items at half the cost. When the permanent cards in the Silver Packs gets substituted with 1500 Req Points Req Cards, then you should instead emphasise on opening Gold Packs and the Gold Packs will guarantee at least 2 permanent cards in the Ultra Rare or Legendary rarity category.
When it comes to obtaining Req Points, a fairly good method is to play Mythic Warzone Firefight as one game gives in average a bit more than 3700 Req Points which is approximately double the req point payout seen in the (Heroic) Warzone Firefight playlist.