Complete Monster: Most of the Shadowen are bad, but their leader, Rimmer Dall, is in a class of his own. From his position as The Federation's FirstSeeker, Dall enforces the state's xenophobic, expansionist policies, enslaving the Dwarves, suppressing resistance, and arresting magic-users, whom he drains of their magics and then, should they survive, throws into The Pit. When Quickening gives the Dwarves hope by healing the Meade Gardens, he sends PeEll to assassinate her. When the Elves return to the Four Lands, Dall dispatches the Creepers to wage a war of extermination against them. He personally tries to murder Walker Boh and Cogline, then sends the Four Horsemen after them, resulting in Cogline's death. He plays a long psychological game with Par and Coll Ohmsford, aimed at shatteringPar'smind and making him susceptible to a Grand Theft Me. Dallís crowning achievement, however, was the construction of Southwatch, a living tower that drained the life from the world itself, and would have, if left unchecked, resulted in the Four Lands becoming an apocalyptic wasteland, inhabited by nothing save a few, maddened Shadowen. Concerned only with his personal power and desire to feed on the strongest magics available, Rimmer Dall wreaked more devastation on the Four Lands than any villain before or since, inflicting damage that has taken centuries to even begin recovering from.
Iron Woobie: Walker Boh loses an arm, his mentor and pet, and the girl he was trying to protect, is forced to become what he hates, and then loses his mentor again, only shortly after having reunited with him.
Paranoia Fuel: The Shadowen can possess anyone and mimic anything. End result, most of the characters are extremely nervous of trusting anybody. Morgan in particular has no faith in anyone following the incident with Teel.
Referenced by...: The The Elder Scrolls franchise, in the form of Morrowind. Not only is that name extremely similar to the island of Morrowindl, the island's volcanic fate is precisely the same as Vvardenfell's and the activities of the Elves there would fit right in with those of the Dunmer. Considering Elf Queen was published in 1992, two years before the first Elder Scrolls game, it's entirely possible the gamemakers had read the Heritage series and were doing Shout Outs.
What happened to Matty Roh is bad enough, but it's very strongly implied if not outright stated that the Shadowen sickness she stumbled into not only disfigured and ruined her feet, it's what caused her entire family and all the neighbors in her valley to get sick and die...in which case she indirectly caused the deaths of everyone she loved by bringing it back with her.