Callidus Assassin

A model with this special rule has a 4+ invulnerable save.

This Model can never have a Warlord Trait. During deployment, you can set this model up in concealment instead of placing it on the battlefield. At the end of any of your movement phases, this model can reveal it's position - set it up anywhere on the battlefield that is more then 9" from any enemy model.

If your Warlord has the IMPERIUM keyword (excluding FALLEN), you can include this unit in your army as part
of a Vanguard Detachment even if that Detachment contains no HQ units. If you do so, that Detachment’s Command Benefits are changed to ‘None’ and its Restrictions are changed to ‘This Detachment cannot include the same datasheet more than once.’

If your army is Battle-forged, you can include 1 AGENT OF THE IMPERIUM unit in each IMPERIUM (excluding FALLEN) Patrol, Battalion and Brigade Detachment in your army without those units taking up slots in those Detachments. The inclusion of an AGENT OF THE IMPERIUM unit does not prevent other units from their Detachment from benefiting from Detachment abilities (e.g. Chapter Tactics, Defenders of Humanity etc.), 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, Battalion or Brigade 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.