Halo 5‘s Warzone Firefight expansion, the Xbox One shooter’s biggest since launch, is coming out at the end of the month. In 343’s latest weekly blog post, the developer shared a status update for how it’s coming along and teased more about what it contains.

“A wide variety of teams are hard at work to get their final work and polish completed,” 343 said. “These include the Warzone team, who are finishing up the PvE mode, the Warzone Boss Refresh we first mentioned in the last issue, and more.”

343 also released images of some of the new Warzone Firefight bosses players will encounter–they look badass. They each have Ultra-class armor, 343 said. Check them out in the images below.

Additionally, while May’s second free update, Hog Wild, did not include any new maps, that won’t be the case for Warzone Firefight. 343 said in the blog post that players can expect “new places,” while the update will also deliver “new tools of destruction.”

Additionally, 343 teased that there are “a few surprises” about the Warzone Firefight expansion that have not been announced yet. One of these could be related to Forge.

343 shared the image below, which appears to suggest the 7 Wood melee weapon might be making a comeback. 343’s Tom French said about the teaser image, “No idea what it might be for.”

The full blog post contains other details about what went on at 343 and across the Halo universe this week. Check it out here.

Warzone Firefight will be Halo 5’s seventh free expansion. The other ones were The Battle of Shadow and Light (November), Cartographer’s Gift (December), Infinity’s Armor (January), Hammer Storm (February), Ghosts of Meridian (April), Memories of Reach (May), and Hog Wild (May).