Maybe Gnome Hunters are a group of gnome hating Ice Trolls from Dun Morogh covered in the bones of dead gnomes who've been eating Leper Gnomes and mutating into monstrous super trolls, decked out in gnome skulls and ready to eat any gnome that moves while addicted to eating leper gnomes?
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Pandaren also never fought the Scourge, safe from that war in their isolation. Unless one or two wanderers like Chen were out there.
Pandaren have mastered their emotions and would have been rejected as candidates in the opening WOTLK DK experience for being "weak".
It doesn't make much sense at all.
Goblins would have fought the Scourge left and right, all over Kalimdor and the Eastern Kingdoms. ANYONE WHO FOUGHT THEM AND DIED was raised in battle. If they had unusual skill in ability, they were candidates for being a DK. Worgen have a special modification in their experience to explain it, having to do with the Worgen of Grizzly Hills in Northrend.