It runs for 46 hours. Plenty of time to get the ribbons.
The info from the events sneak peek:
Hero's Path - Face the Hydra
Deck Restriction: Standard
Opt-In Time: 03/26/2020 06:00 UTC
Start Time: 03/26/2020 12:00 UTC
End Time: 03/28/2020 10:00 UTC