Voidsmen-at-Arms

If your army is Battle-forged, you can include one Agent of the Imperium unit in each Imperium (excluding Fallen units) Patrol, Boarding Patrol, Battalion, Brigade and Arks of Omen Detachment in your army without those units taking up Battlefield Role slots in those Detachments. The inclusion of an Agent of the Imperium unit does not prevent other units from their Detachment benefiting from Detachment abilities (e.g. Chapter Tactics), and it does not prevent other units from your army benefiting from abilities that require every model in your army to have that ability (e.g. Combat Doctrines). An Agent of the Imperium unit included in a Patrol, Boarding Patrol, Battalion, Brigade or Arks of Omen Detachment in this manner is ignored for any rules that state all units from that Detachment must have at least one Faction keyword in common (e.g. in a matched play game), and when determining your Army Faction.

An Agent of the Imperium unit can never be included in a Brood Brothers Detachment

Each time a model in this unit makes a ranged attack that targets a unit within 12", an unmodified hit roll of 6 scores one additional hit.

If your army is Battle-forged, this unit cannot be used as a compulsory selection in a Detachment (e.g. as the only Troops unit in a Patrol Detachment), unless that Detachment is a Navis Imperialis Detachment.