A Command Squad is a squad of Space Marine veterans who accompany the Brother-Captain or other senior leaders such as a Librarian or Chaplain into battle. The exact name of the squad can vary from chapter to chapter, based on customs or tradition, but their function is largely the same. Serving in a command squad is a great honor as the members are often hand picked by the commander, not only for their combat skills but also for their tactical brilliance. Such a prestigious honor always speeds promotion within the chapter, thought this is not without risk. Accompanying the marine commander, the squad will often fight where the battle is the thickest and most wrought with peril.
The members of a Command Squad are known as Honoured Brothers, and members of a command squad are as follows: the Veteran Sergeant (which is sometimes not included), the Company Champion, Standard Bearer, and Apothecary, along with one or two veterans. The Veteran Sergeant will serve as second-in-command to the Captain, but it is rare for the Veteran-Sergeant to succeed the Captain as commander of the Company, though isn't unheard of. The Company Champion is the bodyguard of the Captain. While your average Captain is a human killing machine, the Company Champion will be charged with fighting enemy warlords and champions, allowing the Captain to better focus on coordinating the battle. If there isn't a Veteran Sergeant, the Company Champion will be the acting leader of the Command Squad when the Captain is absent. The Company Standard Bearer will be given the title of "Ancient" and protect the Company Standard from all harm. So if an enemy manages to kill the Standard Bearer and steal/defile the Standard, every Marine in the company will be honor bound to kill the one who did. So basically, the Space Marines were going to kill you, but now you had to go and make it personal. The Veteran will often serve as an adjutant or equerry to the commander.
The Company Champion will always enter combat with a combat shield and power weapon of some variety. The other members of the squad are allowed to take their pick of the company's armory. Unlike other veteran squads such as the Sternguard or Vanguard, members of the Command Squad (excluding the Champion and Apothecary) are not singularly restricted to ranged or melee weapons. However, they may not take heavy weapons.
Command Squads may take to the field mounted on Bikes should they choose. This is preferable for chapters who specialize in mounted assaults.
For 90pts you get an escort unit of vets with reasonable options. The entire squad(with the exception of Apothecary and Champion)(no longer true! Per the new FAQ, the Apoth can be kitted like the rest of the squad. Edit: Games Workshop clarified the FAQ, saying they had made a mistake, and the Apothecary cannot be kitted out like the rest of the squad) can take melee weapons and storm shields each in the same manner as Vanguard Vets. The squad's main strength is the FNP from the Apothecary. The squad's small size also makes it easy to fit into a Razorback or other transport with your leader.
The entire squad has the option to take bikes, making them all the more deadly.
A word of caution on the Company Champion. You're getting a WS5 marine with a free power weapon, however his combat shield only gives him a 6++ save and can't be replaced by a storm shield.
Thanks to the FAQ, every Veteran can now take a SPECIAL weapon, not just a RANGED weapon, which means shooty Command Squads are now a thing that can happen, and are in fact the best way to field them. What does this mean for you? With a Drop Pod, it means five Meltaguns dropping down behind your enemy's Land Raider on Turn One, costing 75 points less than the tank. Add in Vulkan He'stan for Master-Crafted Meltaguns, and you'll be laughing. If you can land the Drop Pod in a way so that some doors can't be opened and thus block LoS, even better! (The Ultramarines and Star Phantoms object to you calling on a special character for your re-rolling needs.)
Whilst you totally COULD mix-and-match the weapons, it's generally better to specialise the squad for one purpose that it does WELL, rather than two or three purposes that it does ok at.
There's also the 'Flamethrower Lawnmower', wherein 5 Salamanders Command Squad Veterans take Flamers for hilarious results against Orks, Guardsmen or Tyranids, or 'Terminators, What Terminators?', with 5 Grav-Guns for between 10 and 15 Grav shots, depending if they moved.
- 5 Flamers are 115
- 5 Meltaguns are 140
- 5 Grav-Guns are 165
Not bad cost for mauling Land Raiders ( 25% chance to strip 5 HP in one turn ( You can't take out exactly 4 unless the target is immune to immobilized, but in that case this strategy becomes largely invalid ), 54% to strip 3 ( Hello Russes ) ), Paladins and Riptides.