Thunderwear

One of the items needed for the 522 warlock set is a zone drop, is this true for any other classes? I haven't tried yet but It might work just to farm the trash in the beginning of the raid.

The 5 Piece, Tier 15 sets from Throne of Thunder are token based.

iLvL 502 (LFR), 522, and 535 (HC) pieces can all be purchased with the following shared tokens:

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  • Paladins, Priests and Warlocks share tokens of the crackling conqueror
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  • Warriors, Hunters and Shaman and Monks share tokens of the crackling protector
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  • Rogues, Mages, Druids and Death Knights share tokens of the crackling vanquisher
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There are 69 sets in this tier.

To my surprise, you can get this achievement by collecting a full Tier set appearance of another class with the same armor type as the one you are playing.

I had three more pieces to get for the Rogue set, when I killed Tortos today the achievement completed. I checked my appearances tab and it turns out I have all parts Monk's Tier 15 set without realizing.