https://www.gamespot.com/articles/destiny-2-trials-of-the-nine-what-is-it-how-to-get/1100-6453377/

One of the regular ways to mix up your Crucible fun in Destiny 2 is Trials of the Nine. This limited-time mode runs on weekends--except when it was canceled because of an emote lets you exploit your way into walls--and provides access to a new area and special rewards. Following the Leviathan Raid's launch on computers, PC players will soon get their first taste of Trials. Here's what you need to know about it.

Trials is a special Crucible playlist that opens up on Fridays at 10 AM PT / 1 PM ET / 5 PM GMT (4 AM AET on Saturday) and is available until the following weekly reset on Tuesday. The specifics of the mode and map you'll play vary; each week features one map and either the Survival or Countdown mode. What never changes is that it's always 4v4 and involves trying to accumulate a total of seven wins before you lose three. Your progress is tracked on a "Ticket" that can be seen in the Director. You won't start picking up losses on your record until you've won a match.