I cant damage a master shadow. It just keeps on draining me of my strength! I am fairly new to this 3rd ed game. I have a cleric, mage/monk, fighter, thief/ranger all around 2nd level.
become a little bit higher level around 4-5 or so before taking on a master shadow and plus have magical weapons because they cant be hit by regular weapons.
Try using your cleric to turn but chance slim and the use fighter type to block the master shadow then hit it with Magic missile spells and from Wand. Merf acid arrow works well when hits.