What’s the name of this movie?

I remember watch an animation film about a post apocaliptic fantasy world or something where the bad guys (i dont remember if they were orcs) find old ww2 weapons and fight with dwarfs.
Also i remember two scenes in wich two of the dwarfs are in a trench and when they came out the camera stays still and a river of blood came down, and (i think this is the final scene) the good mage kills the bad one with a german ww1/ww2 gun a luger or something