Lead from the back.

Lead from the Back
Subtract 1 from hit rolls for attacks made with
melee weapons if the target is a friendly
SKAVEN HERO that is not a MONSTER and is within 3" of any friendly SKAVEN
units that have 3 or more models.

In Skaven society, the rear of a formation is seen as a position of honour, This is so that
a warlord can use their underlines as a living shield.