Direct answer: Swiftest Showdown runs from September 23 at 07:00 UTC until the October 8 maintenance. Complete the Main Quest Open the Waterway, then clear the daily Time Attack Challenge and its missions for up to 2,400 Star Fragments plus Gold.
How does the event unlock?
The Time Attack Challenge opens sequentially from Day 1 through Day 6 during the event. Completing each day’s challenge grants its challenge reward; mission rewards come from the separate Time Attack Challenge! Missions track.
What are the rewards?
- Challenge Completion Reward: Star Fragment x1,800 and Gold x480,000.
- Time Attack Challenge! Missions Completion Reward: Star Fragment x600.
- The listed amounts are the maximum available for completing all challenges and missions.
What should I remember?
Rewards cannot be claimed after the event ends, so complete and claim the available missions before the October 8 maintenance. The official notice does not state a ranking reward or a new character banner for this event.
Update Eve Check-In · Koo and the Two Fools · Events Schedule
Official source: Swiftest Showdown: Time Attack Challenge!.