The Mark X Tacticus armour is the standard power armour of the Primaris Space Marines, introduced when Roboute Guilliman rolled out his new breed of Astartes. It replaces the older Marks VI, VII and VIII for most Chapters, and its big selling point is modularity: the same core suit can be reconfigured for different battlefield roles.
What the Mark X actually is
Mark X isn’t one fixed suit. It’s a family of armour built around a shared core, with role-specific add-ons bolted on. The three main variants you’ll see named are Tacticus (the generalist line infantry suit), Phobos (lighter, stealth-oriented) and Gravis (heavier, tougher).
Tacticus is the middle ground and by far the most common. It’s what most Intercessors, Hellblasters and similar Primaris squads wear. If you’ve seen a Primaris Marine on a tabletop, it’s probably Tacticus.
Why it matters
For ten thousand years, Space Marine armour was a fixed pattern. You wore Mk VII, you liked it, you kept it until it broke. Mark X changed that. The suit is designed to be rebuilt and re-roled, which suits the way Primaris were deployed: flexible, fast, and able to swap from line duty to specialist work without a whole new suit.
It also marks a clear visual and technological break from the Heresy-era designs. Older armour is revered, relic-grade and often irreplaceable. Mark X is new production, made with Cawl’s improved manufacturing, and that shift is a big part of why some traditionalist Chapters were uneasy about it at first.
How it compares to older marks
Older Marks were built for a specific job at a specific time. Mk VI Corvus was stealthy, Mk VII Aquila was the workhorse, Mk VIII Errant added extra neck and chest protection. Mark X takes that logic and turns it into a system rather than a single suit.
The trade-off is that Mark X isn’t as venerated. A Mk VII suit might be centuries old and carry a Chapter’s history. A Mk X suit is equipment. That difference matters in the lore, even if it doesn’t change much on the tabletop.
| Mark | Role | Notes |
|---|---|---|
| Mk VI Corvus | Stealth/recon | Beakie helmet, lighter build |
| Mk VII Aquila | General line | The classic 40k Marine look |
| Mk VIII Errant | Heavy line | Extra armour on chest and neck |
| Mk X Tacticus | Modular generalist | Primaris standard, swappable parts |
Where it fits in the wider lore
Mark X arrived with the Ultima Founding and the Indomitus Crusade. It’s tied directly to Belisarius Cawl’s work and Guilliman’s attempt to rebuild the Imperium’s military after the Great Rift opened.
Because it’s modular, it also connects to the wider Primaris range: Phobos armour for Reivers and Infiltrators, Gravis for Aggressors and Heavy Intercessors, and Tacticus for the core battleline. They’re all the same family, just tuned differently.
- Standard armour of the Primaris Space Marines
- Three main variants: Tacticus, Phobos, Gravis
- Modular by design, unlike older fixed Marks
- Introduced during the Ultima Founding and Indomitus Crusade
- Associated with Belisarius Cawl and Roboute Guilliman
Key facts
- Mark X Tacticus is the standard power armour of the Primaris Space Marines
- It’s a modular system, not a single fixed suit
- Three main variants exist: Tacticus, Phobos and Gravis
- It was introduced during the Ultima Founding and Indomitus Crusade
- It’s tied to Belisarius Cawl’s work and Roboute Guilliman’s reforms
FAQ
Is Mark X Tacticus the same as Primaris armour?
It’s the main Primaris armour pattern, but not the only one. Phobos and Gravis are also Mark X, just built for different roles.
Can Firstborn Marines wear Mark X?
In the lore it’s Primaris issue. Some sources show it being adapted, but it’s designed around Primaris physiology and Cawl’s manufacturing.
What’s the difference between Tacticus and Gravis?
Gravis is bulkier and more heavily armoured, meant for frontline brawlers. Tacticus is the lighter, more flexible generalist suit.