The “Bucket List” WoW achievement locations
You should first clear all the area (kill all the mobs and bosses prior to Shannox). There are some mobs that you can ignore though.
The ones that don’t attack you.
Then pull Shannox and kite him to the places that are marked on the map.
It helps if you are a ranged class.
Get some speed and avoid his hits. Shannox hits pretty hard.