yea, use this:
events: unit dies
conditions: unit type of dying unit equal to *mob*
actions: if,then,else multiple functions
if: integer comparison => math random number => random number between 1 and 100 = less then or equal to XX
then: item - create item at position of dying unit
else: DoNothing
if u want more items to drop at once, make more 'if,then,else's' in that same trigger