Trolls

Considered a refinement of both their previous failures combined, night elves and orcs, the trolls were created in a new attempt to attain immortality for the Elven people. It worked, kind of. Trolls possess a profound ability to heal and regenerate that renders most injuries and illnesses temporary, overcome only by being wholly incinerated or disintegrated.
The first genertion of trolls were living elves, infused with a pattern of magic that rendered them effectively immortal. On the surface this would answer the deeply rooted desire of the elves to regain what had been lost to them by coming to Lorgaire. These enhancements proved to be imperfect patterns however, the regenerating life force that prevented the trolls from dying had the flawed result of rebuilding them not as who they were previously, but simply being reassembled approximately from what was readily available. A troll could be born to resemble a perfect elven child, who without injury or illness could grow to be indistinguishable from an elven adult. Exposed to the challenges of life, the many iterations of regenerative healing small and large they would edure would instead result in their transformation into insane monstrosities. A troll injured and rebuilt again and gain was like a vase put together from fragments of hundreds of different pieces of pottery.
Like the orcs, elves hunt trolls who wander near their territory and wage war on troll communities that grow too large. Unlike the orcs, trolls breed no faster than elves, so their populations remain quite small and they typically inhabit places deemed unsuitable by most other races. Often reduced to being driven by the elves most primal instincts trolls roam and devour anything weaker than them, with particularly savage and insane individuals even resorting to cannibalism.
The immortality lusted after by so many elves takes a disturbing turn as displayed by the trolls. Few would desire to last forever if doomed to forget who and what you are. Rumors and myths persist among some elven tribes hoever, that the transformative weave imbued upon the trolls is not inherently flawed, or that some of the original clade survive to this day with memory and guise intact, thousands of years old, not wishing to share their secret.
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Originally written for 2024 Summer Camp challenge answering Species A SPECIES WITH PROTECTIVE ANATOMY