Demon submitted this

If you want to have more powerfull creatures you can throw eg: a warlock of your own in your prison. Your creatures DO rise as a skeleton. But that takes a while. If you want it to go faster, you can slap this this monster untill he has only one stripe of his little sun above his head. Then let him starve. After a while this monster will change into a skeleton (they train very fast)

What - the low-budget-imps are a fraud?!!