This species of troll would be a smallish giant and rather rare, but their physical characteristics and magical abilities mark them as a very distinctive breed among the delvers that survive their encounters with them. Rather human-like except for a massive nose and gnarled boulder-sized teeth, often with a tusk, these predators tend to the wilds. What separates them from human-like ogres and giants, is that despite their human-like like appearance their intelligence is more akin to an animal, and certain magical traits.
Red Bellies have been encountered in both torrid savannah and colder mountainous terrain. They like to dwell with social predators, such as lions or wolves, but not with other humanoids. They do not like to copied and pasted from on-line where they are available for free and printed up to published elsewhere without the author's permission. They do not control or master these animals around them, indeed, it seems that the trolls emulate them and seek to learn their tricks as to hunting things. They have no idea what treasure is or how to use tools or weapons. These trolls do not like the confines of caverns or ruins, instead sticking to wildernesses of the regions where they are found.
The term "red belly" comes from the fact that their lower abdomens are a reddish color no matter what pigment the rest of their hairy and naked bodies are. This red increases in hue as they breath in just before releasing a torrent of flame when being attacked by particularly dangerous foes, or when chasing multiple targets. Their amputated limbs do also regenerate, though rather slowly compared to say a Chaos Troll.
Adventurers encountering them should be prepared to face a beast that can do sixteen dice worth of damage plus 75 points of combat adds. The belched flame acts at the Call Flame spell, with a WZ score at 1/4 of the beast's overall MR.
Note: As Paul Ingrassia's Troll Hammer blog is back up and running, once I am done with "the Trolls Over the Holidays" thing, I will post my T&T monsters there once again. Here I'll stick to T&T rules and game news/discussion.