Wanted to say the same. Whole-body Shrinka’
This toy makes your character tiny and also do only a portion of damage for a few mins. You can buy it from an npc named Ravika, she is in front of Orgrimmar before you first go to the Broken Isles.
So alliance players have to level a horde character up till the legion preparation event to be able to buy it. But since toys are account wide, after that you can use it on any alliance character, no problem.
Have you checked Wowhead comments sections for these achievs? I’ve found lots of useful tips there in the past for doing low-level content on OPed chars.