There is a second signal in this faction's names, and it is worth naming precisely because it is worthless.
Three detachments share the word Brood: Purestrain Broodswarm, Biosanctic Broodsurge and Brood Brothers Auxilia.
If that stem meant anything, it would sort them into a family. It does not. Look at what is actually true:
- Purestrain Broodswarm and Biosanctic Broodsurge are the illegal pair.
- Purestrain Broodswarm and Brood Brothers Auxilia are the pairing we recommend most, covered on its own page.
Same stem, opposite answers. Brood Brothers Auxilia carries no Unique Tag at all.
The same lesson runs through the other tag pair. Xenocult Masses carries HOSTS and has nothing in its name to say so, while Host of Ascension carries HOSTS and does. Across all four tagged detachments, the name tells you the truth exactly half the time, which is worse than useless, because it is confident and wrong as often as it is confident and right.
And the reverse mistake is just as available. Two detachments that both carry a tag are perfectly legal together if the tags differ. Purestrain Broodswarm plus Xenocult Masses is legal, costs 2 DP, and is ruled out by players who have correctly learned that this faction has tags and then drawn the wrong conclusion from it.
The rule to carry away: check the tag line, not the name.