REMINDER: The S5 battle pass free track will be unavailable after this week

As the title says, you will need to purchase the pass to continue progress on it when the Combined Arms operation launches next week. If you have already purchased the S5 pass, you will be able to switch between it and other passes as normal.

The Combined Arms operation will last five weeks (ends Dec 19, when Winter Contingency launches) and will have its own free 20 item track to progress on, a premium option will be available to unlock a premium-only item, keep the operation pass forever, award bonus xp during the duration of the operation, and to unlock an extra challenge slot for the duration of the operation.

For more information on Operations, see this Waypoint article.