The Destiny beta will start a limited time event today that adds two new maps to the game, developer Bungie has announced in its most recent weekly update.

If you’ve played the Destiny alpha and are currently playing the beta, you’ve probably noticed that it’s missing the Rusted Lands map for the game’s competitive multiplayer mode, the Crucible. Today’s event, The Iron Banner, will see the return of that map as well as a brand new one, Blind Watch, which is set on Mars.

The Iron Banner is also a bit different from the normal multiplayer mode. “Bring your absolute best gear because we turn on Level Advantages,” Bungie Designer Lars Bakken said. “That means your Attack and Defense ratings matters in Iron Banner matches.” The event also has limited time rewards, so winning a match might be your only opportunity to win a certain weapon.

The Iron Banner begins on Saturday, July 19 at 2:00 p.m. Pacific Daylight Time. It will remain open for only two hours. If you want to see the new maps, you better clear your schedule, because Bungie said this will be the only way to see them during the beta.

Bungie has not yet decided if progress from the beta will carry over to the final game. However, if you play the beta after 8 p.m. Pacific on Saturday, July 26, you will receive an exclusive emblem for use in Destiny when it’s released on September 9.

The beta runs from now until July 27 at 11:59 p.m. Pacific, though it will be offline on July 21 and 22. Xbox One and Xbox 360 owners will be able to join the beta on July 23 at 10 a.m. Pacific.