In this post, I would like to share with you my experience with the Necron Resurrection Orb, and hopefully shave some time of your learning curve. If your new to Necrons, then you probably are doing exactly what I did when I first started playing them. Take two units of Warriors and a Lord with a Resurrection Orb as the base and then working the rest of your army around the 6" Orb range?
Before 5th Edition, Necron Warriors had the ability to Hold up most units in the assault quite well with their high leadership and WWB rolls. In those days Troops were not scoring and it was quite feasible to throw in a unit of Warriors to hold up the enemy ready to teleport them out and leave the enemy stranded for the rapid fire. Of course with a Resurrection Orb Lord nearby to give WWB rolls on those power weapons really made a difference.
Things have changed now with 5th edition, and with the new losing assault/sweeping advance rules, the Necron Warrior will not hold up in the assault regardless of having an orb around or not. Over the years of playing Necrons and using the Orb I almost became dependent on it, and the one most biggest thing I have learnt recently is not to take an Orb! The Orb restricts your thinking so much, and not having it, frees you up for so much more. No more huddling around the Orb meant that I could start thinking in the 4th dimension when it came to the new 5th edition missions and going out to contest objectives.
The Orb doesn't just give you a WWB roll with power weapons, but also with instant death weapons as well. If someone does decide to shoot those Lascannons and Missiles Launchers at your Warriors as oppose to your Destroyers or Monoliths for some reason, just make sure you get cover saves using terrain or other units as best you can, and don't forget you can go to ground as well for a 3+ cover save. The other option is to reserve your Warriors, cutting down on a couple of rounds of shooting.
Nowadays, I mainly use a Destroyer Lord joined to a unit of Scarabs Swarms as a delivery system for the still fantastic Necron wargear. Being free to move around the board distracting my opponent and splitting the units if needed, is so much better than the Orb Huddle, and gives you so much freedom.