The Mystery Cards are now live! Craft standard badges to get the Mystery Cards for the event badges (normal and foil) that will be craftable on December 21th when the Steam Winter Sale 2023 is starting!

Link: (to buy Mystery cards from the Steam Community Market)
Steam Winter Sale 2023

More info about the Myster Cards:
1) SteamCardExchange[www.steamcardexchange.net]
2) SteamDB[steamdb.info]

Happy (pre-)crafting!