Allied Factions in Warhammer 40K 11th Edition — All 5 Rules

Most Warhammer 40,000 armies are mono-faction. But five specific alliance rules let you bring units from outside your codex, and each one works differently — different eligibility, different caps, different restrictions on what those units can do once they are in your list. Getting one wrong is a straightforward way to fail a list check.

This guide covers all five: who qualifies, how many units you get, and what the allied models are forbidden from doing.

The five alliance rules

Note that no army can ally *into itself* — an Imperial Knights army does not take Freeblades, an Agents of the Imperium army does not take Assigned Agents.

Assigned Agents

If your army Faction is IMPERIUM but not Agents of the Imperium, you can include Agents of the Imperium units. The allowance is split into three categories, and each scales with battle size:

These are three separate budgets, not a total. At Strike Force you can bring two Retinue units, two Characters and one Requisitioned unit — five allied units in one list — as long as each category stays inside its own cap.

The category a given Agents datasheet falls into is printed on the datasheet, not derived from its keywords, so it is worth checking rather than guessing.

Anathema Psykana

The narrowest rule: Adeptus Custodes armies can include Anathema Psykana units from the Custodes codex. There are no subcategories — it is a single total.

Because the units come from the Custodes codex itself, this is the most seamless of the five rules — no cross-codex bookkeeping.

Freeblades and Dreadblades

These two are mirror images, and they are the ones that break people's expectations, so read carefully.

Freeblades: if *every model in your army* has the IMPERIUM keyword, you may include either 1 Titanic Imperial Knights model or up to 3 Armiger models.

Dreadblades: if *every model in your army* has the CHAOS keyword, you may include either 1 Titanic Chaos Knights model or up to 3 War Dog models.

Three things trip lists up here:

It is exclusive-or, not both. One Titanic *or* up to three of the small ones. You cannot take a Titanic Knight and an Armiger alongside it. This is the single most common mistake with these rules.

The limits do not scale with battle size. Unlike every other alliance rule, Freeblades and Dreadblades give you the same allowance at Incursion, Strike Force and Onslaught. Three Armigers at 1,000 points is the same three Armigers at 3,000.

"Every model" means every model. If any model in your army lacks the IMPERIUM keyword, Freeblades is off. This is why Freeblades and Assigned Agents can conflict in practice — check that the Agents units you brought actually carry IMPERIUM.

And in both cases, the allied Knights:

Corsairs and Travelling Players

The Drukhari rule, and the only one that works on a points budget rather than a unit count. Drukhari armies can include Harlequins and Anhrathe units up to a combined points limit:

There is a significant exception. If your army uses the Reaper's Wager detachment, that rule *replaces* Corsairs and Travelling Players with a different deal: you may take Harlequins only — no Anhrathe — but the points allowance roughly doubles:

At Strike Force that is half your army. Reaper's Wager is less an alliance rule than a different way to build a list.

One further wrinkle: under the standard Corsairs rule, allied Aeldari units cannot receive Enhancements. Under Reaper's Wager they can. If you are planning an Enhancement on a Harlequin Character, the detachment choice decides whether that is legal.

The rules that apply across all five

Some constraints recur, and it is worth internalising them as a set:

Should you ally at all?

The honest answer for most lists is no. Alliance rules cost you internal synergy: allied units usually do not benefit from your detachment's army rule, and they rarely have the keywords your buffs are looking for. A 200-point allied unit that sits outside all of your re-rolls is often worse than a 200-point unit from your own codex that sits inside them.

The cases where allying is genuinely right:

Checking it in a builder

Every limit above is mechanical, and GrimSlate enforces them: category caps for Agents, per-battle-size totals for Anathema Psykana, the exclusive-or for Freeblades and Dreadblades, the points allowance for Corsairs including the Reaper's Wager swap, and the Enhancement eligibility rules that follow from each.

You can start a list free and turn alliances on from the roster settings — the app will only offer the alliance rules your primary faction actually qualifies for.

Quick reference