Act as an independant Physician unit for the Beastmen Confederate forces.
Cast many high level White Magic and Red Mage spells on their allies within area of effect.
They seem to shed a players enmity rather quickly unlike most campaign enemies, if their attention is not kept they will easily de-aggro.
Fiendish Leechkeeper's do not aggro unless acted upon. If a player acts upon a Leechkeeper gaining enmity, it can link to ANY other Campaign enemies nearby of any type.