As with all units in this volume, assassins are forced to be loyalists in terms of their faction. Indeed, the entire book might as well as have the word Loyalist in the title to be maximally descriptive.
The assassins themselves can never be a detachment or army on their own. They can only ever be taken by using the Clade Operative prime advantage. If a loyalist army does this, then they gain 3 support slots that can only be filled with assassins, and only once in a prime detachment.
Whether this is worth doing or not is dependent on many factors.
In a large game, they're probably not worth it in my view. A single assassin is unlikely to be taking out a squad of terminators. However, in lower points games where one-on-one match ups are a bit more valuable and impactful, they can do extremely well. I would therefore recommend them for narrative play and up to (e.g.) 1500 points to play around with. Although the sacrifice of the Prime Advantage is steep to purchase them in such games as well.
They all come with a Divisio Tactica called Nemesis. This means that any incoming shots are snap shots unless made by the closest unit. This gives the assassin a bit of breathing room to operate in, but doesn't make them invulnerable. Yet they remain vulnerable to volleys and precision shots by the same token. This ties in with their fluff: they wear a body glove which helps them disguise themselves against their background - hence my recent paint scheme using a glitch camo approach for my Vindicare. All of them are also heedless - they can never take or contest objectives. Their personal missions are beyond such petty concerns!
Overall then, the rules for assassins get a middle of the road 3/5 from me. We will look at the individual assassins in the next suite of posts.
