There are two distinct variants of "horde VS legion". The Classic variant takes elements from DotA and puts them into the world of Savage 2. Both teams need to upgrade their troops and waypoints in order to overwhelm the enemy. The latest version of hvl (hvl 2) comes with a new game concept and tons of new features. Both teams need to capture and control the sectors on the map in order to advance their technology and unlock new abilities.
This is the beta version of HvL. Unpack the downloaded file into your "~/savage2/game/maps" folder. Then start the game and join any of the Horde VS Legion servers.