To be a janitor on Holy Terra, you need to be the best of the best of the best of the best. And that's what the Captain-Commanders are. Take a look at their upcoming rules for 40k in this preview of the Adeptus Custodes codex.
From the article:
The Adeptus Custodes codex is up for pre-order this Saturday, and it’s chock full of awesome new tactical options to make your elite army even elite-ier.
With new HQ options inbound, there are more ways than ever to lead your Talons of the Emperor in battle. On top of that, you can now upgrade a standard Shield-Captain model to be a Captain-Commander, granting them a host of new abilities that make them even more effective – if you can imagine that.
Each type of Shield-Captain has access to three unique abilities and you, as their commander, can simply pay the points to upgrade them and choose the one you like. This allows you to easily bend your leaders towards certain battlefield roles. Let’s take a look at a few to give you an idea of their potential.