Bungie have decided to upgrade Gambit game mode to Gambit Prime as they added new roles that will help with separate parts of the match and armour sets which will help to fulfil the newly assigned roles. Did we just see Master Chief?
Bungie are looking to refresh and possibly improve Destiny 2's PvPvE game mode Gambit that was introduced with Forsaken. Gambit Prime will feature four distinct classes on top of being changed to a one-round competition. The classes are Reaper, Collector, Sentry and Invader.
Reapers will have mostly green armour and be in charge of mowing down enemy waves and it appears like their assigned armour will provide bonuses that will help them do the job better, just like with the other classes. In the case of Reapers, players will get to weaken High-Value Targets, their multi-kills will generate special ammo and killing powerful enemies will recharge their grenades.
Sentries will be yellow and their multi-kills will increase damage against Taken. As the name suggests, they will be on a bit more defensive role as the rest of their bonuses focus on helping their allies. Therefore, Sentries will be able to mark Invaders for teammates, buff said teammates in well of light and Bank will give health Regen.
Speaking of Invaders, their colour will be red and they will be able to generate ammo while invading, get a more powerful overshield as well as damage bonus when killing enemy Guardians. Their ability to steal motes will be crucial as Invaders can lock the motes down drain them.
Collectors will be white and they are another support role. This role is entirely focused on playing around motes - the first bonus is that motes will grant overshield, another one will give ammunition when depositing motes and holding 20 motes will send in a giant Blocker.
The last ability from the Collectors seems to be just as good as Invaders' ability to steal motes. Collectors will not be stealing anything though, but dying while holding motes will not mean they are lost forever as Collectors will drop any motes they had.
You can find more info and different possible colours for each armour set on the official post from Bungie.