The two units that we'll be discussing are the Devastator Centurians and the Thunderfire Cannon. Both give us huge torrent of fire capabilities, though each have their strengths against different types of opponents. I'll get into the why's at a later date, but I'm going to assume that you're sticking to the 3-man Centurian squad to keep costs down. Stock, that is about 190 points (rumored). If you upgrade your weaponry to Cyclone Missile Launchers, you're adding about 30-45 points (don't recall exactly...irrelevant anyway). That gives us 15 grav cannon shots and 6 missiles per turn, per unit. Not bad at all. These guys are excellent at killing MCs and MEQ. Centurians do have 5 toughness, 2 wounds, and 2+ armor saves. But they don't have invulnerable saves, which is really their Achilles' Heel. For reference purposes, the rules for Grav weaponry are below.
-Have the Concussive special rule
-Weapons are not Blast weapons.
-Wound the target based on their Armor Save. For example, a terminator
has a 2+ save so they would be wounded on a die roll of 2+. Against
vehicles roll a die, 1-5 does nothing and on a 6 the vehicle is
Immobilized and loses a Hull Point.
Grav Pistol: Range 12" AP:2, Concussive
Grav Rifle: 18" salvo 2/3 AP:2, Concussive
Grav Cannon: 24" salvo 3/5 AP:2 Concussive
Grav Amp: Re-roll failed To-Wound and Armor Penetration rolls for Grav weapons.
Which brings us to our big question: Do we take 2 3-man Centurian squads and 1 Thunderfire Cannon for MEQ/MC busting power? Or 1 3-man Centurian squad and 2 Thunderfire Cannons for horde control? Keep in mind that Nids are rumored to be the next codex released, with the Orcs following shortly behind them. The meta-game could very well shift towards hordes. Or it could make MCs ultra-powerful. Its a tough choice and I'd like to hear your thoughts on it. Note: I'm leaning towards the 2x Centurians/1x Thunderfire Cannon. ;)
In addition, please see this thread for other important info regarding Implausible Nature.