Giant Rats and Packmasters fight in mixed units. In these units, Packmasters and any, character that joins the unit can be placed anywhere within the unit (but they normally tend toaccumulate towards the back..). Missile hits and impact hits against these units are randomised as follows: roll a D6, 1-5 hits a Giant Rat, 6 hits a Packmaster.

Remember that you use the best Leadership in the unit to take Leadership tests, so the Giant Rats won't need to use their own Leadership as long as one Packmaster is alive.