If you have fewer than 40 knowledge in this you'll only spawn the lesser non-rare versions needed for Elusive Beasts of the Dragon Isles. In order to get the rare version of mobs to spawn you must have 40 knowledge spent in Mastery. The Elusive rares needed for this achievement can be summoned at specific locations by using Elusive Creature Bait. Comment by YariniCeteriBig thanks to Selbink-Area52, Sayerel-Area52, Jurvicious-WyrmestAccord and Trauk-Blackrock for helping find the spawn locations of all these rares and massively cut down on skinning time by grouping up.
