The War Javelin is a javelin-type rangedweapon which knocks back all enemies in its path and can even be used to teleport after being thrown. This item is exclusive to the Rise of the Giant DLC.
Impaler can be used with this item to back enemies into walls and then teleport to them, allowing Impaler to crit, though this method is slightly unreliable.
The War Javelin can also be used to teleport to enemies after attacking a few times, allowing the player to initiate the fight with the later attacks of a weapon's combo.
This is usually useful for weapons which have the majority of their damage located at the last few hits, such as Giantkiller.
The War Javelin also will let slower weapons, such as the Broadsword, to get more hits of their combo in.
When using Ammo, the player will first throw the second War Javelin before being able to teleport. After reactivating the weapon, the player will usually teleport to the first War Javelin if the second one is still traveling in the air.
If the Javelin is placed in the backpack, and the mutation Acrobatipack is applied, the javelin can be thrown multiple times without being collected or returned. The teleporting function of the Javelin is also ignored.