Rarity
Sold by Shopkeeper. One particular Broker has taken a liking to the skrat species, kept this rare specimin as a pet, and inherited the smell as a souvenir. Critter type. To get the Pet you'll need to access a "hidden" vendor in the second room of the instance.
Rarity is a battle pet sold by a hidden Shopkeeper NPC inside the Shadowlands dungeon Tazavesh, the Veiled Market, requiring gold and three specific lockboxes to purchase.
Guide awaiting review
Gather the Three Lockboxes
Before entering the dungeon, collect a 
Oxxein Lockbox from Maldraxxus, a 
Solenium Lockbox from Bastion, and a 
Phaedrum Lockbox from Ardenweald. If you don't have them, pickpocketing enemies in those zones is a reliable method — all three can be obtained within a few hours.
Enter Tazavesh and Find the Shopkeeper
Enter Tazavesh, the Veiled Market and defeat the first boss. After the boss, run down the stairs to the right — the Shopkeeper is in the right corner of that room, located to the northeast of the Customs Enforcement building, across from the Questionable Trader. You do not need to have cleared the dungeon yourself; you can join someone who has already cleared it and use their instance to access the Shopkeeper.
Unlock the Shopkeeper's Inventory
Stand near the Shopkeeper and he will whisper 'Psst. Hey, you. Unassuming visitor. Do you like small creatures?' — however, this alone does not open his shop. To trigger his inventory, interact with the nearby pets: /pet the cat named Curiosity (who roams the area), the skrat named Goblin (found behind a nearby tree), and the Corgi Bartender named Waffles inside Myza's Oasis behind the bar. Use /target to locate each of them.
Type /yes to Trade
Once the Shopkeeper triggers his dialog, target him and type /yes in chat to unlock his trading interface. Purchase Rarity using your three lockboxes and the required gold.
Open Lockboxes Carefully
When opening the lockboxes as part of the transaction, turn off autoloot first and leave an item inside each chest — the trade will still complete successfully.
Tips
You must be the group leader for the Shopkeeper's dialog to trigger — if you are only a party member, the interaction may not fire.
See the video guide for a full visual walkthrough of the Shopkeeper's location and the pet interaction steps.
