Gutterrunner

From BelegarthWiki

Gutter Runners are skilled at infiltrating behind enemy lines, scouting ahead of the main Skaven force and hiding in a position that will allow them to jump out at the right moment to ambush the crew of enemy war engines, or to cut down enemy officers. Sometimes these stealthy fighters use the tunnels that made up the labyrinthine Skaven Under-Empire to make an unexpected attack on the vulnerable rear of an enemy force.