https://www.wowhead.com/item=90087 is an item dropped by https://www.wowhead.com/npc=66936 in Pandaria’s Krasarang Wilds. This NPC can be summoned by the use of an item called https://www.wowhead.com/item=90172. To make this item, you will first need to loot fragments for this item from 6 other makrura-type NPCs:

/way The Jade Forest:Pandaria 59.8, 95.8 Akkalar
/way The Jade Forest:Pandaria 59.2, 36.6 Akkalou
/way Dread Wastes:Pandaria 27.0, 69.0 Clamstok
/way Krasarang Wilds:Pandaria 39.4, 88.6 Damlak
/way Kun-Lai Summit 42.4, 24.0 Kishak
/way Kun-Lai Summit 54.2, 21.6 Kishak
/way Townlong Steppes 42.6, 92.6 Odd'nirok

After obtaining all 6 items, you will be able to fuse them together to create the https://www.wowhead.com/item=90172. Then you can make your way over to Krasarang Wilds.

/way Krasarang Wilds:Pandaria 12.6, 82.0 Clawlord Kril'mandar

Use the item to summon https://www.wowhead.com/npc=66936. Upon defeat, the item https://www.wowhead.com/item=90087 will drop.

If you loot this item, bear in mind that there must always be.. a Pinch King.