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Space Marine 2’s Chaos Siege Mode arrives with Patch 15 on 1 October 2026, and it is free: Saber announced it as part of Year 3’s free content. You play as Chaos Space Marines on a new Siege map on Avarax, hold out against Tyranid and Loyalist waves, and can deploy a Helbrute. Here is what that means next to the Siege you can play today, and what Saber has not shown yet.
TL;DR
- Release: 1 October 2026, with Patch 15 (the Second Anniversary Update). Season Pass 3 launches the same day.
- Price: announced as free Year 3 content. Season Pass 3 covers cosmetic DLC and is a separate purchase.
- The mode: Chaos Space Marines on a new Avarax Siege map, against Tyranid and Loyalist waves, supported by Chaos Cultists and Ritualists, with a Helbrute you can deploy.
- The flip: in today’s Siege the Helbrute is an enemy; in Chaos Siege it is on your side.
- Not shown yet: Chaos Marine classes, rewards and progression, difficulty, and whether you control the Helbrute directly.
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Chaos Siege Release Date and Price
Focus Entertainment dated Patch 15 for 1 October 2026, and Saber’s August Community Update puts Chaos Siege in that patch. The same post says Season Pass 3 “will also be available on the same day” as the Second Anniversary Update.
On price, the June Community Update lists the Chaos “spin-off” of Siege under “the free content that will be added in Year 3”, and only after that turns to “the cosmetic DLCs” of Season Pass 3. So the mode itself is free; Season Pass 3 is the paid cosmetic side of Year 3.
Anyone who would rather not spend the evenings on it can hand Space Marine 2 boosting to our crew instead — same account, same progress, played by hand.
What Is Chaos Siege Mode?
Saber’s description is one paragraph: “In this mode, you’ll play with Chaos Space Marines on a brand new Siege map located on Avarax. You’ll face Tyranids and Loyalists waves, receive the support of Chaos Cultists and Ritualists, and you’ll be able to deploy a Helbrute to wreak havoc on the battlefield.”
The June update framed it the same way: you will play “characters that were once limited to PvP only”. Until now Chaos Marines have been playable only in Eternal War, and the closest thing to a playable Helbrute was Patch 10.0’s Helbrute Onslaught, a PvP mode.
Chaos Siege vs Regular Siege
Regular Siege is the free wave mode on Kadaku; our Siege Mode guide covers its shop, wave scaling and bosses. Side by side, the announced differences look like this.
| Regular Siege | Chaos Siege (Patch 15) | |
|---|---|---|
| You play | Loyalist Space Marine classes | Chaos Space Marines |
| Map | Imperial fortress on Kadaku, three rotating sectors | New Siege map on Avarax |
| Enemy waves | Tyranids and Thousand Sons | Tyranids and Loyalists |
| Your support | Summoned elite Space Marines, Cadian Troopers, a Dreadnought | Chaos Cultists and Ritualists |
| Helbrute | Enemy | Yours to deploy; direct control not stated |
| Price | Free | Announced as free Year 3 content |
Regular Siege facts: enemies and the Helbrute from Saber’s Siege launch announcement, reinforcements from the Patch 8.0 notes.
What Saber Has Not Shown Yet
- Which Chaos Marine classes or loadouts you get.
- Whether your class levels, perks, weapons or cosmetics carry over, or the mode has its own progression.
- Rewards, currency and unlocks.
- Difficulty tiers and squad size.
- Whether “deploy a Helbrute” means an AI ally you call in or one you pilot, as in Helbrute Onslaught.
The mode is not out, so there is no build or “best class” advice here. We will update this page from the Patch 15 notes on release.
All Weapons + Currency
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What Else Ships in Patch 15
- Crucible Mode: Penances for Purity XP; entry needs a level-25 class. Crucible breakdown.
- One-Handed Thunder Hammer and the Tactical rework: the hammer comes to Tactical, Assault, Bulwark and Techmarine; Tactical’s perk tree becomes “more diverse” and it can trade its primary for a Power Sword, Power Axe or the new hammer. Tactical rework preview.
- Year 3: Patch 15 is the first of five major updates, Patches 15 to 19 (May Community Update). Year 3 roadmap.
Our Take: Is Chaos Siege Worth Waiting For?
Our Take
The most interesting idea in Patch 15, and the least explained.
Holding a line as Chaos, with Cultists at your side and the Helbrute that used to charge you now charging for you, is a real change from Siege on Kadaku, and it costs nothing. Whether it lasts depends on what Saber has not shown: classes, progression and rewards. Until the Patch 15 notes are out, it is a promising paragraph rather than a mode to plan around.
Sources and Confidence
| Claim | Source | Status |
|---|---|---|
| Patch 15 on 1 October 2026 | Focus Entertainment on X, 12 Sep 2026 | Official |
| Chaos Siege: Chaos Marines, Avarax, Tyranid and Loyalist waves, Cultists, Ritualists, Helbrute; Season Pass 3 the same day | Saber, August Community Update, Steam, 28 Aug 2026 | Official |
| Chaos Siege listed as free Year 3 content; Season Pass 3 = cosmetic DLC | Saber, June Community Update, Steam, 25 Jun 2026 | Official |
| Regular Siege: Tyranid and Thousand Sons waves, Helbrutes as enemies | Saber, The Siege Update, Steam, 26 Jun 2025 | Official |
| Regular Siege reinforcements: elite Space Marines, Cadian Troopers, Dreadnought | Patch Notes 8.0, Steam, 26 Jun 2025 | Official |
| Five Year 3 updates, Patches 15 to 19 | Saber, May Community Update, Steam, 29 May 2026 | Official |
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