Strength not added?
What?
He has a Bite and a Claw which both use his considerable strength.
Only the 6 Vine attacks dont' use his strength, but they don't do any damage regardless, they are just to fatigue the unit so it can be easily hit by the rampaging deady.
I personally love the Carrion Dragon, as he can switch modes if you come into contact with someone who you can't use brute strength to beat do, you switch him to a Pan (with respectable hit points) throw some armor and weapons on him and can fight off the new threat. And if he gets in a bad position, switch to a Dragon and foam at the mouth.