Box art of the Spearhead: Stormcast Eternals box set. It depicts the contents as 16 miniatures: Yndrasta, a Knight Vexillor, 3 Annihilators, a Stormstrike Chariot, and 10 Vanquishers.

This new "Spearhead" box for the Stormcast Eternals strikes me as an odd one. I get why it exists - it makes it easier (and maybe "cheaper"?) to get hold of some otherwise harder to get/expensive models - namely Yndrasta, the push-fit Annihilators, and the Knight-Vexillor - which are were only available online via Warhammer.com, and were previously only available in the Age of Sigmar 3.0 launch box. With AOS 4 coming this summer, all that makes sense. It's the "Spearhead" distinction that's got me scratching my head…

Conceptually the new box looks a lot like the Vanguard sets each faction apart from Stormcast Eternals already have: a character, a big unit of Battleline troops, a smaller unit, and a support piece or third unit. The contents here are somewhat dictated by Yndrasta and friends coming on a single sprue, giving an extra character but that's by-the-by. The Kruleboyz Orruk Warclans Vanguard box has the same limitation (and other similarities) but is still a Vanguard box. And other factions are getting Spearhead boxes too, according to the article:

we’re reliably informed that plenty of other factions from across the Mortal Realms will be getting their own Spearhead boxes in due course

Warhammer Community

I am noting the conspicuous use of "plenty" and not "every"… we'll come back to that later.

So, what do I think is going on? Well, I think there are 2 main options*, and for both we need to look at recent 40K developments.

In 9th Edition Warhammer 40,000, Combat Patrol was the smallest game size officially supported by the rules; it used a smaller board and a points limit of 500 points. Each Combat Patrol box set was supposed to be a roughly 500 points starting point for a faction that would fit into this game mode, but you didn't have to use the boxes, any valid 500 point army was usable. As sets were released the "idea "roughly 500 points" idea kind of went out the window as Combat Patrols kept ramping up in power - the Custodes set was approximately 1300 points at the time, if memory serves. When Age of Sigmar 3 launched the summer after 9th edition, Vanguard was introduced as a comparable game size and range of "starter" boxes.

Fast-forward to 10th edition last year, and Combat Patrol was completely reworked. It's no longer "just" a 500 point game of 40K. Instead, it's a completely distinct game mode, using the same core rules but different faction rules. There are no points limits; each Combat Patrol box acts as a "pre-made" force, similar to pre-made decks in some card-based games, with no variation in units or wargear allowed. You play Combat Patrol only with the contents of a Combat Patrol box as depicted on the front of the box** - other units are not permitted. The faction rules are written in an attempt to balance each box against the others, despite the apparent disparity in power between sets.

Finally, we have this cryptic opening line to the article:

There will soon be an even easier way to muster the immortal warriors of Sigmar for tabletop battles against the worst the Mortal Realms can throw at you.

Warhammer Community

All this is to say, I think Spearhead is the Combat Patrol for AOS4. Why ditch the Vanguard name? Honestly, I'd suggest it's "naming congestion"; Stormcasts have an entire sub-range of "Vanguard <whatevers>". Space Marines have a new Vanguard <something or other> set that's not a Combat Patrol.

But I said there were 2 options, so what's the second?

In the run-up to 10th edition there was a narrative series called Arks of Omen. It brought with it a new game mode to 9th Edition***, called Boarding Actions, that was accompanied by box sets for most/all 40K factions called Boarding Patrols. In terms of list-building, Boarding Actions was a fusion of 9th Edition Combat Patrol and 10th Edition Combat Patrol, played on a special game board to represent the inside of a ship. It was still 500 points of 40K, but lists were chosen from a pre-determined subset of units, and the faction rules were different to "main" 40K. The Boarding Patrol boxes weren't necessary to play, they were just a thematic selection of units. There was a lot of auxiliary material published in White Dwarf, and basically it was a fun addition to the 40K side of the hobby.

Arks of Omen kicked off around about January last year, so the timing would be more-or-less right for an AOS version, if it were coming. But it would have to land this month. There's already a narrative event underway for AOS - Dawnbringers - which could then flow into whatever the Spearhead boxes are for. It would mean that Vanguard boxes aren't going away (probably), though I'd still put money on a similar revamp as Combat Patrol received. I even remarked at the time - on my now deleted Twitter account - that I'd love to see an AOS version of Boarding Actions, perhaps representing the inside of a Stormvault or something. But despite that I think this is the less-likely option of the two.

The tenuous reason I think there might be a slim chance it's this "Boarding Actions for AOS", is the fact the article didn't say "every" faction was getting a Spearhead. If I remember rightly, some 40K factions didn't receive a Boarding Patrol box - Imperial Guard spring to mind (Imperial Agents got a box instead), so we could see something similar here.

If there is a similar small-scale game mode coming to AOS to bridge 3rd and 4th editions, I don't think it's going to be as comprehensive as Boarding Actions - certainly not with a new game board or terrain, otherwise we'd have seen some sort of teaser for it. Arks of Omen was teased months in advance of release. Fitting that in before the summer, in a way that's satisfying to players, feels too much this late in the cycle. It's with that in mind that I think it's most likely the first option of a Combat Patrol-style revamp of the existing Vanguard boxes.

But GW have been known to completely surprise us on occasion, so I guess we'll have to wait and see?

* There is a 3rd, boring option - that it's just a random name given to a new set of "value added" box sets, with no interesting link to the game or narrative. But that's no fun to speculate about!

** some sets, like Custodes and (I think) Grey Knights require you to choose from a predetermined subset of the units in the box, for balance purposes.

*** It's technically still compatible with 10th Edition too.