Greatheart, by Dixie Lee McKeone, paperback Birthright novel
“When gnolls attack a caravan of humans heading toward the Sielwode Forest, only young Cald Dasheft survives. Perhaps a worse fate awaits him, though. He is found by the dreaded Sielwode elves, who intend to slay him. They know that even a single human child suffered to live could one day destroy the great heart of the forest.
But the elves also know compassion.
Now, Cald has grown to manhood among the elves. He has proven himself a brave and skilled warrior, though to many elves, his is still an outsider.
Even so, worse outsiders are entering the forest. In a sacred grove of twisted trees, a portal has opened to the Shadow World, and undead are pouring from it. These otherworldly invaders would be bad enough by themselves, though their very presence has caught the attention of the Gorgon, who wishes to lay claim to these undead armies.
Gnolls, undead, the Gorgon…and one elf-raised human boy. Who will bring about the Sielwode’s destruction – and who will become its Greatheart?”