Editing Warhammer 40,000/9th Edition Tactics/Necrons (section)

===Command points===
We have a few amazing Stratagems listed in their own section, another thing to keep in mind is that the game is about VP, not CP.

Wound rolls for attacks that cause multiple wounds and only need a 3+ are another good use of CP, as are the number of wounds a weapon causes (if it causes D6 wounds and you rolled a 1,) invulnerable saving throws for multiple wound models against wounds that cause multiple damage, quantum shielding rolls against attacks with a damage of 4 or higher. 

When conducting your Shooting and Assault phases you should consider when a re-roll might be most effective, re-rolling a wound roll for a Gauss Pylon yields an average of 6.66 additional (often unsavable) wounds. Re-rolling a wound roll for a Doomsday Ark will yield an average of 2.31 (again often unsavable) wounds. Wasting a re-roll to kill that last Chaos Space Marine when you could use that CP to re-roll the number of wounds needed to kill off Magnus would be silly, so shoot with the things that benefit most from re-rolls first. Assault is a lot more complicated, but unless you need to think of other things, such as enemy units possibly making a counter-attack, you should also attack first with the units that benefit most from re-rolls. 

On the matter of large formations, as stated before you will get excellent ways to increase your firepower, with more units making for better effects, also, if you are operating blobs you may find Insane Bravery very convenient to make your warriors or immortal formations stand their ground, in turn allowing Ghost Arks and Technomancers to do their job at bringing your stuff back to life.

In general, you want to re-roll as late in the process of doing unsaved wounds as possible. Take Heavy Gauss Cannon for example. Re-rolling a hit roll yields 0.67 hits or 0.5 hits depending on the platform. But re-rolling a wound roll will always yield a hit. Re-rolling a 1 on a D6 is usually always a good idea, number of wounds for a Gauss Destructor, C'tan Antimatter Meteor, or a Doomsday Arks number of shots.

You want to use your command points as early in the game as possible without wasting them. If we assume that a command point is worth 20 pts and both players have 6 command points then by turn 4 if one player has used all his CP and his opponent has used 2 he is essentially ahead by 80 pts. The thing about these small advantages early game is that they snowball, so if you manage to destroy just a little more of your opponent's army on the first turn than he does of yours, he is going to be having that little bit less to shoot you with next turn. If you keep ahead by using your command points as soon as you have a good use for them and you avoid keeping units in reserve you can make this snowball effect work for you. Those 200 points spiral into 250, then 400 and suddenly you're ahead by 600 pts because you used the forces and assets at your disposal instead of saving them for a rainy day that may never come.