Look at how & where they are created & rewarded in Rewards.cs / Smith Rewards in the calculator & constructors. That should give you a guideline on setting the others up for power scrolls.
The Name = "a skeleton"; isn't the only one you need to change. There are at least 3 more places in the script that say skeleton. And its also best to make a copy of the script & change the copy & then also change the copy's name as well.