https://www.polygon.com/2018/6/28/17514462/destiny-2-faction-rallies-exotic-catalyst-sweet-business-graviton-lance-sunshot

The new update to Faction Rallies in Destiny 2 has been a bit polarizing for players. Some seem to hate the grind while others enjoy it (with some exceptions). But no matter how you feel about the new system, the pressure to grind every time it comes around feels real if you want all the rewards. Thankfully, Bungie has come out and confirmed that catalysts — the most desirable Faction Rallies rewards — will still be achievable in Year Two of Destiny 2, although we don’t know how.

If you don’t want to miss out on the three exotic catalysts for sale during season 3, you’ll need to turn in at least 3,000 tokens over the three different Faction Rallies — 1,000 for each faction. If you miss a Faction Rally or don’t have the time to hit 50 ranks in a single week, then you’re out of luck if you want all three before season’s end.