The bosses in Elden Ring Nightreign are already pretty tough. But if you’ve gotten good and need a harder challenge, you’ll be able to take on “Everdark Sovereigns,” which are more difficult versions of the game’s Nightlord foes you face to conclude a run.

“These limited-time versions of the Nightlords are extremely challenging and pose an even greater threat to the Nightfarers with new moves and increased power,” according to a blog post from Bandai Namco.

The first Everdark Sovereign you can fight is a new version of Adel, Baron of the Night, aka Gaping Jaw. If you’ve beaten the normal version of that boss, you’ll be able to take on the new form. When you beat an Everdark Sovereign, you’ll get “Sovereign Sigils,” which you can exchange for “special Relics and other items.”

There are a couple caveats to be aware of. You can only fight Everdark Sovereigns while playing online. And Everdark Sovereigns will only be available for a limited time — the upgraded Gaping Jaw, for example, will stick around until June 25th at 8:59 PM ET.

Bandai Namco says a new Everdark Sovereign will be added every week, and over the “next few weeks,” Everdark versions of Sentient Pest and Darkdrift Knight will be added to the game. Other Everdark bosses will be added “at a later date.” Based on the blog post, it seems like Everdark variations will eventually return after they’ve disappeared.

At some point, the game will also get DLC that adds new playable characters and bosses. An Elden Ring movie is in the works, too.