The Scourge have a set of two heavy tanks that fill in your heavy choices when building your army. I have found these to very easily create variant lists on controlling the game on the ground. Lets take a look at the two very different heavy grav tanks for the Scourge.
Slayer HGT Squadron
There are different ways to try and control the ground, and the best is the use of anti-armor tanks. The Hunter is the standard very fast, Scourge tank. It comes in at 37pts, while the heavy Slayer hits 54pts. You can take these guys at 6 per squad, where the hunter you can take 9.
The Slayer comes with twin-plasma cannons that fire 12" with a move and fire of 6", so can fire twice. It also comes with two damage points. Plasma Cannons are demolisher-2, and squadrons of these tanks can level buildings rather quicky.
The Slayer is the most efficient use of firepower for the points, as it comes with twin-plasma cannons, so gets two shots to the hunters single shot cannon. Where the hunter excels is in its speed over the Slayer.
For heavy hitting right now on the ground, I have been showing preference to the smaller of the two in my games. Mostly due to the speed of the tanks, as I have been walking my Hunters on the board a lot of late. However, if you were to invest in the Slayer its a nice heavy hitting tank that would work great as a front line heavy hitter. It would take some dedication though in my book.
The problem I have had with Slayers is that they come with the same armor of the hunter, and when hit, have a good chance of taking 2pts of damage when being hit by anti-tank guns. So the ground game for me becomes more of a trying to stay moving and avoid getting this, rather than taking the punches on the front line going toe to toe with enemy tanks.
The Tormentor HGT Squadron
This is a tank that I just love. Its not a front line vehicle, but needs to get up close to it, in fact right behind it. The Tormentor is a flamer tank, that can clear out many infantry with just two tanks hitting the building. If you are playing against the scourge, I highly suggest not getting into any buildings active Tormentors on the ground.
This tank literally gets 10 E4 shots with an accuracy of 3+ for clearing out enemy occupied buildings. with a range of 6" and a move and fire of 6", it can have a surprising range of death for infantry trying to take a building away.
Overall Scourge heavy tanks have issues going head to head with other heavy tanks from the other factions. This is why I prefer the lighter Hunter over the Slayer, but the Slayer has its uses. The other races have guns with longer ranges, so when Scourge tanks go head to head, unless its a fast and quick hit and move on, Scourge tanks are often on the short end of the stick. Of course there are cards that greatly change this up, and can be game changers with your tanks hitting hard in the open.
Razorworms
I saved these for last. Each heavy tank can carry a base of razorworms. These are good at taking on bulidings, and everytime I field a heavy tank I tend to include them. Often never getting to deploy them. A razorworm base can start eating points up very fast at 36pts a base, but also for that cost are very good infantry killers.
Where I have had the best success with razorworms, is when using them in Tormentors. Torching a building of enemy infantry and then killing off the survivors with by injecting razorworms. Razorworms do offer an advantage in that you get some extra hard hitting infantry in areas of the table that your primary infantry are not available.