Dark Sun: The Scorched World of Athas
A troll is an extinct species on Athas but many still live in the Lands Within the Wind where they eat anything that moves, from grubs to humans. It is rightly feared for its ravenous appetite, feral cunning, and remarkable regenerative power. They are highly adaptable and resilient, making their homes almost anywhere.
Trolls hunt most other living creatures and are unconcerned about the size or numbers of their prey. They regenerate quickly, even after they are slain. Their regeneration is so powerful, in fact, that trolls can regrow severed body parts. Only fire or acid can kill a troll, and trolls have a healthy fear of fire and acid for these reasons.
Trolls wade into the midst of its enemies, relying on regeneration to keep it alive. Trolls are not clever, and they usually attack whichever enemy last did the most harm. Trolls usually fight to the death but will sometimes flee from opponents using fire.