Rockworm balance

@Tarma2 I do agree that Nod Rockworm is a little on the strong side when the appropriate counter units are not available to combat them, this is a big issue around 400-1000 Nod or GDI. GDI in particular struggles with the Rockworm until they have the Orca or Kodiak with Missile Squads/Jumpjet Trooper. and Zone Troopers being a soft counter to them. But I am surprised to hear you have difficulty with them as Nod being that the Nod Cyborg is one of the more potent counters to the Rockworm as their EMP particle beams not only slow down the Rockworm if not before it retreats but also decreases its attack speed further reducing its combat effectiveness. Pair them with some anti infantry support such as Militants, Flame Troopers or Confessor Canals and you have a very tough pair that can almost handle anything thrown at it as Cyborgs counter any vehicle and aircraft threats, while your anti infantry squad handles your enemy infantry squads.  

If by chance you cannot tech up the Nod Laser Soldiers in groups of two do a decent job of taking down a Rockworm just make sure if the Rockworm is coming to the missile control pad, if you can spare the time move them away one tile from the exit point of the Rockworm to avoid the Rockworm emergenance AOE damage to your anti vehicle troops. 

If they are becoming an almost every game occurrence for your matches I would definitely consider training and when possible leveling up your Laser Soldiers or Cyborgs so you have more of an edge in terms of Health and Damage against the Rockworm.