Outside the Slaughtered Lamb
The Slaughtered Lamb[46, 83.8]
is a seedy pub in the Mage Quarter of Stormwind City. The pub's basement and catacombs serve as host to the city's warlock community and acts as a training ground for new recruits. The top floor is abandoned except for a bartender. Given the pub's name, it seems like the perfect place for warlocks to do their training.
The Slaughtered Lamb is presumably named after a pub of the same name that appears in the film An American Werewolf in London.