I did that mission, and didn't have to find a specific body - first you have to see the Will O' the wisps, then find the room on the first section of the cave where there are about 7 skeletons, zombies and various corpses, then kill the trolls.
Worked fine for me. Sorry if this isn't any help.
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I hate the mice from Bagpuss. Never trust rodents with DIY skills.
"We will fix it, we will fix, we will stick it with glue, glue, glue, we will stickle it, every little bit of it, we will fix it like new, new new."
::SQUISH::
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