On the other hand the Tervigon is a model which absolutely needs a model of his own. Although a Carnifex can be used as an effective proxy (I use one myself) it's really a poor looking substitute compared to the picture in the codex. I'm 100% sure that if GW would come out with a decent looking model the sales on it would be fantastic. It's rules are just that good. Since GW won't do it then another company has;
Everyone knows about the Spawn Termagants rule. That's the one that allows it to "poop" out 3d6 Termagants. It's a great rule that's very flavorfull to the spirit of the codex and effective on the battlefield. The Brood Progenitor rule is another one that may not be as famous as the one that allows it to poop out models but is twice as awesome. It gives Termagants within 6 inches the rule counter-attack and if the Tervigon has Toxin Sacks and Adrenal Gland bestows poison attacks and furious charge on them too. I wrote a post on some tactics with that rule earlier.
In addition this beast also comes with the Psychic power Dominion. It's nice but I've never used it once. My Termagants usually aren't very far so I rarely need to extend Synapse out to 18 inches. The Psychic power I use a lot is Catalyst. I'm also willing to be that it's probably the most often used Psychic power in the entire codex. Why not, who doesn't love the rule Feel No Pain.
There is one other Psychic power that's rarely used. I just started using it myself and have never seen anyone else use it. Onslaught. It allows a unit to run, then shoot, and then assault if it has fleet. It's a shame that most people (including myself) have long thought of only using it on Termagants. Only recently did I even consider using it on other broods. Here are a few who can benefit the most from it;
- Hive Guard and Zoanthropes- The 24 inch range of their guns has long been lamented as short especially in Dawn of War deployments where they start off the board. The Zoe's Warp Lance is especially limited with only an 18 inch range. Hit them with Onsluaght and the Hive Guard can now move, run and then shoot at a target up to 31 to 36 inches from were they started from. The Warp Lance enjoys a big bonus compared to it's original range and can now threaten from 25 to 30 inches from where it started.
- Harpy- A relatively weak monstrous creature it has to pick and choose who it engages and stay away from those that it does not. Unfortunately to drop it's spore mine cargo it has to move over a unit in the movement phase. That usually leaves it very close to danger. While it's a decent attack it won't wipe out any squad in one blow. That's why a smart player would either forgo the Harpy's shooting and run it into cover or pray to the dice gods that his ballistic skill 3 is good enough (and it usually isn't). With Onslaught the Harpy gets to move into cover and continue to shoot the target he hit before. The D3 spore mines, Stinger Salvo and Twin-Linked Strangelthorn Cannon is a lot of firepower and should break up a unit pretty hard and should not be wasted because of a need to find protective cover.
- Dakkafex- The added d6 range boost is good for a beast with limited range but that's not the only reason you want to hit this guy with Onslaught. It will allow you to keep him shooting and killing things as you move a strength 9 monstrous creature into close combat range. Shooting will slow him down because he won't be able to run leaving you unable to get into assault range. With Onslaught he can do both and maintain his speed while killing your opponents infantry every step of the way.
- Trygon Prime- Not only is the Trygon one of the best models GW has ever produced it's also a fantastic beast on the battlefield. He kills anything he touches. Usually I tell everyone to save the points and only take the Trygon. The only real benefit of the Trygon Prime is the Strength 5 Assault 12 Containment Spines. It's a brutal load of dice and will rack up the kills. Too bad he almost never shoots with it. If he shoots he can no longer fleet and usually that means he's out of range to assault. He's much better assaulting than he is shooting so most people don't shoot. Hit him with Onslaught and he can do both. That gives you the added benefit of softening up your target before the assault. With luck you'll take out a few of the ablative wounds so when your real blows hit he'll be targeting the all important powerfist.