Review: Legiones Astartes Siege Assault Battle Group

Right on time for the holidays, the Legiones Astartes Siege Assault Battlegroup launches an assault on your Christmas money. Here comes our XXL review: are the new Cataphractii Terminators an upgrade or downgrade? We reveal all the build options, have scale comparisons with old and new Terminators, HQ sprue images including the new Breacher Squad upgrade sprue, plus an unboxing video in 4K. Everything you need to know in this post.

The Horus Heresy Lediones Astartes Siege Assault Battle Group will be available for pre-order starting Saturday, 27 December 2025. The pre-order period lasts two weeks, with the official release date set for 10 January 2026. Please note that there will be (likely) only one production run, so the box is available only until stocks last. The RRP is £129 / 170€ / $215.

Included in the box are 23 miniatures:

• 10 MkIII Breacher Squad Space Marines
• 6 Cataphractii Terminators with power mauls and volkite chargers
• 6 Cataphractii Terminators with power fists and combi-bolters
• 1 Leviathan Dreadnought with siege claw and siege drill
• plus 3 Horus Heresy infantry transfer sheets and 1 dreadnough transfer sheet
• plus an assembly guide

Siege Assault Battle Group unboxing

I’ve captured what awaits you when you open the large but slim Horus Heresy Siege Assault Battle Group box in a video. In this, I show you the complete contents, all the sprues, the assembly instructions, the transfer sheets, and a Cataphractii Terminator in 3D. Further down in this post you’ll find a detailed description of all the build options for each kit, as well as high-res sprue images.

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Breacher Squad review

Breacher Squads were one of the most-requested Horus Heresy infantry kits, and now they’re finally available in plastic. In the Siege Assault Battle Group you get a squad with 10 models. This consists of 2 of the existing MkIII Legionaries sprues with 5 models each with bolters.

Additionally, you get the small Legionaries accessories sprue, which contains accessories like melee weapons for the Sergeant, a nuncio-vox and vexilla, as well as bayonets and pistol holsters. This is also familiar from previous kits.

What’s new is the Breacher Squad upgrade sprue, which contains enough parts for 10 models:

• 10 boarding shields
• 10 (identical) helmeted heads
• 1 helmeted Breacher Sergeant head (combines with the plume from the accessories sprue)
• 1 bare head
• 1 breacher charge
• 1 lascutter
• 1 graviton gun
• 10 bolters
• 10 left arms
• 10 right arms
• 10 left hands (boarding shield attachment)

Patreon bonus content: Ultra high-res, uncompressed versions of these sprue images (and backsides of the sprues) can be downloaded here.

You get 10 different arm pairs with shields and weapons. Since the MkIII sprue only has five different poses and is included twice, each pose appears twice. The instructions therefore show two possible arm pair combinations per model/pose. However, the contact points at the shoulders are flat and thus freely compatible. So you can also find combinations other than those in the instructions. You just need to be careful that the shields don’t collide with the legs.

Unfortunetaly, you only get 1 of each special weapon, even though they are a one per five models option in the Liber books.

Note that the arms aren’t kept in a generic design like the melee and special weapons upgrade sprues. Instead, they’re very specifically MkIII, with the rounded elbow armour and reinforced vambraces. This makes sense, of course, because they come with the MkIII Space Marines, and MkIII “Iron” armour is the most heavily armoured suit, perfect for boarding actions. However, anyone who thematically prefers a different mark for their Legion will be out of luck.

Cataphractii Terminator Squad review

The Cataphractii redesign caused quite a stir beforehand… and I was also initially disappointed by the unfamiliar-looking proportions, especially after the redesign of the 40k “Indomitus” Terminators was handled so well. But sometimes models look quite different in person than in two-dimensional photographs…

In the Legiones Astartes Siege Assault Battle Group you get 12 Cataphractii Terminators, 6 of them with power mauls and volkite chargers, 6 of them with power fists and combi-bolters. That’s the first major “innovation” compared to the old kit. The old one had 5 Cataphractii per sprue (with power fists and combi-bolters, pairs of lightning claws, a reaper autocannon, and a power sword for the Sergeant, check our review of the 2nd Edition “Age of Darkness” launch box). This sprue was included twice, so 10 models in total per box.

The new Cataphractii kit has a sprue with two medium-sized segments containing 6 bodies. This is included twice in the box, so 12 bodies. Then you get 1 sprue each with 6 weapon arm pairs: one with power mauls and volkite chargers, and one with power fists and combi-bolters. When the Cataphractii are later available individually, there will presumably be two different boxes with 6 models each, one with power mauls and volkite chargers, and a second box with power fists and combi-bolters.

Let’s first look at the sprue with the bodies. Per sprue you get:

• 6 identical torso units
• 6 different leg pair poses
• 12 top layer shoulder pads with full banding (34), 12 top layer shoulder pads with half banding (35)
• 6 pairs of extra thigh armour with more banding (meant to match shoulder pad design 34), 6 pairs of thigh armour with less banding (meant to match part 35)
• 6 identical helmeted heads
• 2x 3 different optional tilting shields
• For the Sergeant: 1 helmeted head with bionic eye (part 8), 1 bare head with half-mask (9), 1 optional scroll decoration for the chest plate (47), 3 different back icons (44 to 46), 1 grenade harness (48 and 49), 1 optional tilting shield with skull (43)

Patreon bonus content: Ultra high-res, uncompressed versions of these sprue images (and backsides of the sprues) can be downloaded here.

The heads sit on ball joints and can be rotated, as can the hip joint, though here the range of movement is limited to a few millimetres. Variety comes from the optional tilting shields and cosmetic options for the Sergeant. Additionally, you can choose between two slightly different top layer shoulder pads (parts 34 or 35) and thigh armour plates for all six models. You need to look very carefully at the assembly instructions here: for each model/pose it shows two different options, which differ (almost) only in the shoulder pads and matching thigh armour. Also refer to the unboxing video above, where I flip through the entire assembly guide.

The power maul/volkite charger weapons sprue contains:

• 6 right arms with volkite chargers (parts 53 are for the two-part barrels)
• 6 left arms with power mauls
• 1 right arm with reaper autocannon (98 to 100) and extra targeting optic (101)
• For the Sergeant: 1 left hand with power sword, 1 left hand with power axe, 1 left hand with thunder hammer, 1 extended left arm (87), 1 lowered left arm (90)
• 14 left and 14 right halves of the bottom shoulder pad/pteruges layer
• 1 chainfist attachment (although no power fist is included)

There are enough parts to equip the 6 bodies either only with standard weapons, or with one reaper autocannon and one Sergeant with melee weapons. Notice that the hands are smaller than on the old Heresy Terminator models, they’re now exactly the size of the MkII, MkIII and MkVI power-armoured models. Despite the compatiblity, hands and weapons are moulded to the arms, as you can see on the sprue images, which makes kitbashing difficult.

The flat contact points at the shoulders have small nubs that dictate a specific position for the arms. You can remove these for a bit more freedom when positioning (to a certain degree, otherwise the drape of the pteruges leather straps no longer corresponds to gravity). As you’ve probably noticed, the shoulder armour now consist of three parts plus the arm. This initially seems unnecessarily complex, but ensures that the pteruges could be modelled very three-dimensionally. I recommend first gluing the two parts of the lower segment to the arm one after another, as these are precisely tailored to each arm and must click into place in a specific position. As there will be a quite obvious seam line where the two pieces line up, now is the time to fill those seams. Only then should you attach the top layer of the shoulder pad, as it sometimes doesn’t fit together without force the other way round.

The power fist/combi-bolter weapons sprue contains:

• 6 right arms with barrel magazine combi-bolters, 1 right arm with belt-fed combi-bolter (for the Sergeant, part 55), 7 combi-bolter halves (the bolters are two-part)
• 6 left arms with power fists
• 1 right arm with heavy flamer (104 to 106) and extra targeting optic (109)
• For the Sergeant: 1 left hand with power sword, 1 left hand with power axe, 1 left hand with thunder hammer, 1 extended left arm (97), 1 lowered left arm (98)
• 16 left and 16 right halves of the bottom shoulder pad/pteruges layer
• 1 chainfist attachment

An almost identical layout to the other weapons sprue, even though you get one extra weapon arm with combi-bolter including a shoulder pad pair here.

Cataphractii old vs. new size comparison

Here’s a scale and size comparison with various other Terminators and power armoured models. The new Cataphractii are somewhat larger and more upright than the old Cataphractii and Tartaros Terminators. However, the new 40k Indomitus Terminators are still larger and bulkier. I think the proportions fit well with the recently released Legionaries in MkVI, MkIII and MkII armour. You can easily imagine that the new Cataphractii design is based on a similar “skeleton” to MkII and MkIII and was then supplemented with additional armour plating.

Here you can see another comparison with the Saturnine Terminators from the Saturnine box (review here), which still tower over everything else.

My opinion on the new Cataphractii design

As I hinted at the beginning, I didn’t like the new Cataphractii Terminators at first when I watched the Warhammer Preview. The proportions and the narrow hips looked somehow odd…

After having the models in hand, though, I have to revise my judgement (at least partially). I don’t know why the models look so off in pictures, but in person the proportions seem balanced. I think you have to rewire your brain a bit: the new Cataphractii Terminators are perhaps the first Terminators that Games Workshop has released that are (reasonably 😉 anatomically correct. They stand more upright, the torso isn’t weirdly compressed, and if you were to remove the shoulder pads, the shoulders also sit at the correct height. As well-proportioned as the new 40k Terminators are, the torsos are still too short.

On top of that, there are many detail improvements. The pteruges leather strips now all have a fine texture, even on the shoulders, and aren’t just flat strips like on the old models. The exhaust unit on the back is finer detailed and more sharply cast. And the shoulder pads fit precisely on the shoulders and sit where they should be. With the old kit there was a lot of leeway and you never knew 100% where exactly to attach them.

However, the kit still has, in my opinion, one major weakness: the poses, specifically the arms. Whilst the new 40k Terminators have relatively dynamic poses and sense of direction despite their massive armour, many of the Cataphractii’s arms just seem to flap around (either straight down or straight out). This impression is reinforced by the power fists looking a bit too small and puny, especially in combination with the long and massive combi-bolters. The 40k Terminators with their shorter storm bolters and larger power fists seem more balanced in that regard. Perhaps this is where the Cataphractii kit’s more multi-part nature takes its toll. Here you need to experiment more yourself until you get cool poses from the available components.

Leviathan Siege Dreadnought with claws and drill review

Last but not least, there’s also a Leviathan Dreadnought in the box. This is the existing kit. We reviewed the model here, so check that out if you’re not yet familiar with this model.

The Leviathan fits the box’s theme, even though GW’s tendency to recycle older models in army boxes can be somewhat annoying. At least this isn’t the same variant as the ranged weapons Leviathan in the Legiones Astartes: Combat Force box.

Where to get

You can find the latest GW releases at our 🇬🇧/🇪🇺 partner stores Wayland Games, Element Games, and Firestorm Games, at 🇩🇪 Taschengelddieb and PK-Pro, and at 🇺🇸 Noble Knight Games with a welcome discount of up to 20% over RRP. Using our links helps to support Tale of Painters at no additional cost to you, so thank you very much for using them!

I hope you found this review helpful, feel free to leave a reaction or comment below, or post your questions here or discuss on our Discord channel.