In Borean Tundra in the top right before you enter Dragonblight the scourge area has a quest that involves you destroying some red orbs (horde?) these orbs do not fight back, have roughly 1500 HP and level weapon skills.
Probably not the most useful for 2 hander toting classes that can one shot them the second they get a hit in, but for the earlier levels 1-300 its usually pretty nice.
Location of orbs
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