A Question about a challenge

While playing today I received a new weekly challenge named “Clouds of Attachments.” It looks different from all the rest, with a little orange tab at the end with a star and chevrons (similar to the button for “quick play”). Its description says to “earn assists in fiesta matches.”

I do not see “Fiesta” listed under the game modes for ranked, quick play, BTB, custom games or bot bootcamp.

Has any one else received this challenge and does anyone know how to complete it?

The event starts in 10 minutes. You won’t be able to find fiesta until then :]

Cool, I wasn’t aware there was an event coming up. Thanks for the reply.