He, this is my favorite Carnifex configuration. It rarely comes out due to the high points cost, but its just so funny when it hits combat.
Carnifex with Acid Maw, Adrenal Glands (WS and I), Bonded Exoskeleton, Extended carapace, Flesh Hooks, Implant Attack, Regenerate, Re-inforced Chitin, Tail scythe, ThornBack, Toxin Sacs, Toxic Miasma, Tusked. Armed with Crushing Claws and Scything talons.
Total: 282 points.
He's just one big, fat linebreaker. Support him with a few gaunts (or ripper swarms, I've found rippers are excellent paired with a Carnifex), and should be tough enough to reach the enemy lines in one peice. I.ve had this guy get back to full wounds with regeneration after teetering on the brink of death twice!