That is a completely legitimate army list. It is Battle-Forged, and totally legal.
Here's basically how it works:
Detachments - a 'Force Organization Chart'. That is, you're told 1-2 HQ, 2-6 Troops, 0-3 Heavy, etc etc. Combined Arms Detachment is the old standard Force Org that everyone knows and loves.
Formations - a Force Organization Chart where most of the units (if not all) are already assigned for you. For instance, the Stormwing Formation for Space Marines is 1 Stormraven Gunship and 2 Stormtalons. No more, no less. The Librarius Conclave Formation for Space Marines is 3 - 5 Librarians, and you can choose one of those to be Tigurius.
In the case of both Formations and Detachments, you have restrictions and benefits. Command Benefits are things that are granted specifically to the units/models (depending on the wording and your gaming group's interpretation) in each Formation or Detachment.
In your list, the CAD terminators would receive Objective Secured, while all of the models from the Nemesis Strike Force would receive access to the turn 1 chance for Deep Strike, and the shoot/run bonus, but no ObjSec.
Here's basically how it works:
Detachments - a 'Force Organization Chart'. That is, you're told 1-2 HQ, 2-6 Troops, 0-3 Heavy, etc etc. Combined Arms Detachment is the old standard Force Org that everyone knows and loves.
Formations - a Force Organization Chart where most of the units (if not all) are already assigned for you. For instance, the Stormwing Formation for Space Marines is 1 Stormraven Gunship and 2 Stormtalons. No more, no less. The Librarius Conclave Formation for Space Marines is 3 - 5 Librarians, and you can choose one of those to be Tigurius.
In the case of both Formations and Detachments, you have restrictions and benefits. Command Benefits are things that are granted specifically to the units/models (depending on the wording and your gaming group's interpretation) in each Formation or Detachment.
In your list, the CAD terminators would receive Objective Secured, while all of the models from the Nemesis Strike Force would receive access to the turn 1 chance for Deep Strike, and the shoot/run bonus, but no ObjSec.
