Ordo Hereticus to use No Escape when they charge in with high-powered
CC allies. Very nice.
A Bloody Rose Sisters army with Zephyrim, Repentia and Arcos is gross, and when you load in Hereticus Inquisitors to lock their targets. The wording of the rule about including a single Inquisitor in a detachment seems to imply the any detachment can include one in any/every detachment- so up to 3 of them, provided you're actually fielding a full 3 detachments.
Chamber militant synergy needs to happen. Granting the Inquisitor's <Ordo> Keyword to all Chamber Militant units in the same detachment. If the Inquisitor is your warlord, they grant their <Ordo> Keyword to every Chamber Militant unit in the army. This would be especially potent if they didn't lose their own faction abilities. I don't have the Greyknight dex, but from what I hear, they could really use some support.
PA 4 has something for them, but we're not sure how good it will be; Inquisition synergy could have been a safety net to protect against an underwhelming showing in
PA. And of course, a nice boost for Sisters and Deathwatch as well.
I did find one thing in the
WD list somewhat confusing: the rules about not breaking Order Traits/ Doctrines etc. appear under the bullet point point for including single, allied Inquisitors. The bullet point that gives you the rules for including Inquisitorial Detachments includes no mention of whether or not they have a Battle Brothers exemption when fielded this way.
The only detachment that really works for Inquisition is Vanguard, since a) you can only ever include a single inquisitor in a detachment an b) there are no troops choices for Inquisition.
And finally, being able to use any Imperial Transport doesn't necessarily confer the ability to include it in an Inquisitorial Detachment, meaning that an Inquisitor can catch a lift in a Valkyrie, but only if there's a guard detachment in the army.
My personal Inquisition dream is Greyfax, the
SoS character that we're getting in February, and two squads of
SoS Vigilators, all mounted in a Kharon Pattern Acquisitor. Unfortunately, there are no official 8th ed
40k rules for the Acquisitor, though some decent house rules from a fellow Dakkanaut can be found here:
https://www.dakkadakka.com/dakkaforum/posts/list/728744.page