Dance with Catrina to become a skeleton during the Day of the Dead You have from November 1st to the 3rd to get this on done. Visit Wowhead for a great guide.

  Remember you can purchase masks from the holiday vendors! Make sure to do dailies and hit those candy buckets for the tricky treats. Also you don't need to keep them all.    

Allow High Inquisitor Whitemane to cast Mass Resurrection, defeat all revived Scarlet Judicators, and then defeat Whitemane in Scarlet Monastery on Heroic Difficulty. I did find a video you can watch good luck!  

This achievement my take you a while and you'll need some space in your bags.

Defeat Rattlegore without allowing him to gain more than 5 stacks of Rusting in Scholomance on Heroic Difficulty.

Simply find that blue hatchling skyscreamer and Shoo it away. Here's the npc number that you can enter into npc scan 70215

Use a Mogu Statue's Crushing Slam to kill another opponent (mob, critter, bad guy)  

Defeat Houndmaster Braun without killing any hounds in Scarlet Halls on Heroic Difficulty. Remember DO NOT kill any dogs up to the 1st boss.

/Bow to the Shado-Pan Novices when they bow to you after being defeated during the Master Snowdrift event in Shado-Pan Monastery on Heroic Difficulty.

Cause Brother Korloff to light six nearby training dummies on fire,  and then defeat him, in Scarlet Monastery on Heroic Difficulty. It's all about stacking!