Marvel Cosmic Invasion’s Castle Doom Mode: Siege Gauge, 12 Perks and Rewards

Castle Doom is a run-based mode arriving with Marvel Cosmic Invasion’s premium The Siege of Castle Doom DLC on November 10, 2026. Clear encounters, collect Battery Cells and improve your heroes before confronting Doom. If the Siege Gauge fills before the showdown, the run ends.

The mode is still unreleased. This explanation follows Dotemu’s announcement and Tribute Games level designer Kevin Chiasson’s breakdown, rather than a hands-on review.

How do the Siege Gauge and Stabilizer work?

Doom has built a Cosmic Inductor to defeat Annihilus, but its instability threatens Earth. Your team storms his fortress while Reed Richards’ Stabilizer provides the countermeasure.

According to Dotemu, encounters charge the Stabilizer, while rising Siege Gauge pressure makes the opposition stronger. Chiasson says the gauge advances when heroes are bested; successful encounters supply Battery Cells to help stall Doom’s plan. Failure therefore affects the attempt’s remaining prospects, rather than simply sending you into the next room unchanged.

What are the five door types?

Chiasson describes five encounter categories. Choosing a route lets a team weigh immediate survival against equipment and progression:

A failed challenge can leave fighters with a debuff, Dotemu warns. Taking an event door is consequently a different decision from choosing recovery.

Are the 12 perks permanent upgrades?

The announced 12 perks cover offense, defense and tactical benefits. Chiasson explains that selections apply per hero, allowing teammates to coordinate their builds.

Those choices should be distinguished from Reed’s Lab, where permanent unlocks add equipment, events and modifiers for later attempts. The publishers describe both decisions made during a run and changes that expand future runs; they are not interchangeable reward systems.

Dotemu also confirms DoomBots and returning bosses from the base campaign. Chiasson says a successful siege unlocks a new hero color palette. None of those announcements establishes how balanced or replayable the finished mode will feel.

Is Castle Doom free, and which platforms get it?

This is part of the premium DLC, not an announced free update. Dotemu’s release announcement lists PC via Steam, Nintendo Switch, Switch 2, PlayStation 4, PlayStation 5 and Xbox Series X|S for November 10. The same pack adds Doctor Doom and Invisible Woman as playable characters.

The Steam listing confirms that the PC DLC requires Marvel Cosmic Invasion on Steam and is not yet available. An exact worldwide unlock hour and individual territory storefront availability have not been verified.

Check our release calendar for the dated entry and gaming coverage for further confirmed updates.