Witches need scalps for certain spells

So I read a lot about what people were thinking, so I decided to think of an idea that would fit these criteria
1.Not everyone should want to be a witch
2. A town should not want a witch to be among them.
So I was thinking certain spells could require scalps, the better the scalp the higher the chance of the spell working or it has a greater effect. A score under 100 would be completely useless. (not sure if you can still turn it into headsmen afterwards or not if you use a scalp that would qualify for the top ten list)
I think this would be good because not everyone wants to go around scalping everyone, and not many towns will take in murderers. It also means you won't want a witch in a neighboring town either, or any witches on the map for that matter unless they are on your side, but of course keeping a witch fed with scalps would make a lot of enemies. Overall I think it would contribute to a feeling of general dislike of witches/fear of witches and anyone who supports witches.
edit:
Or maybe just to become a witch you need to sign your name on a piece of paper made from a scalp that can go into the devil's black book. Higher the scalp the better (for one reason or another) and maybe a needle to prick your finger to write with your blood.
1.Not everyone should want to be a witch
2. A town should not want a witch to be among them.
So I was thinking certain spells could require scalps, the better the scalp the higher the chance of the spell working or it has a greater effect. A score under 100 would be completely useless. (not sure if you can still turn it into headsmen afterwards or not if you use a scalp that would qualify for the top ten list)
I think this would be good because not everyone wants to go around scalping everyone, and not many towns will take in murderers. It also means you won't want a witch in a neighboring town either, or any witches on the map for that matter unless they are on your side, but of course keeping a witch fed with scalps would make a lot of enemies. Overall I think it would contribute to a feeling of general dislike of witches/fear of witches and anyone who supports witches.
edit:
Or maybe just to become a witch you need to sign your name on a piece of paper made from a scalp that can go into the devil's black book. Higher the scalp the better (for one reason or another) and maybe a needle to prick your finger to write with your blood.