Tervigon Conversion Pictures

I'm going to let the tactial deep-thinking go by the wayside for a little bit since I finally got off my tail and got access to a camera. Here come the tervigons! They're a carnifex kit with warrior scything talons (...I don't see much point in melee upgrades past the double-glands for these guys, but I suppose I could justify Scything Talons) and a foam ball to bulk up the back. Like the Tyrannofexes, I'm going for simple but effective. One of them's even taking a termagant-dump.
Front and back. Mmm, green stuff and foam for the bulking out.

I figure the big tongue works as a toxin-type upgrade. If you look closely at the ribs on the bottom, there's the adrenal gland. With all the other gooey bits up top, I just couldn't find a good spot to slap the gland. The pointy carapace bit servs me again as cluster spines, though I suppose it could also do the Stinger Salvo in a pinch.

Side view; one of them has the talon atached to a chunk of the base and the other's doing just fine.

And finally, a bit of a top view. If I shot directly from the top, well, there'd be the shadow from my hand and all.

I know there's no way they'd actually fit the 20 bajillion termagants in there, and the max production they could make out over the course of a game is 15 per turn (that's a 4, 5, and 6, so no doubles) for seven turns, or 105 termagants. There's no way you're fitting that much space into anything you really want to field and justifying it being able to move under its own power.

I figure that the tervigons carry a crap-ton of embryos, and then use some kind of internal fuel source to rapidly hatch them and grow them and fire them out. Thus, when you see doubles, it's the fuel source burning down, or some other internal ammo-depleted type of deal.