Training Dummies are mechanical NPCs that enables you to test your dps out on different level mobs. Training dummies are located in all capital cities.
There are also level 3 Training Dummies in Eversong Woods, Elwynn Forest, Durotar, Trisfal Glades, Mulgore, Teldrassil, Dun Morogh, Kezan and Azuremyst Isle.