Apprentices don't get randoms, just Warlocks do. And any unit out in the field hunting is automatically on combat duty.
You can script Apprentices for Leech or Hellbind Heart, but that won't help against Gargoyles or Golems, etc.
Demonbred in the field scripted for Infernal Prison (they can cast it with 2 slaves) is a pretty nice disincentive for raiding SCs.