Verse 18 reads sorcerer in my New American Standard. I have several versions. But let me just start by saying that the versions issue is a false dichotomy. Several of the most modern translations, (post 1970), use earlier manuscript evidence than the KJV. Yet they substantially agree.

The critics should be ashamed that they are still using this warnout and utterly baseless arguement. You could not translate any literary work (even the cat in the hat) from one language to another using two completely independent translators and come up with verbatim copies. That is not the point. The point is... did the translator give a faithful account of the original. With the exception of some cults twisting it to their own doctrinal ends, by far most modern day translations agree and I would challenge anybody to put forth a specific incidence where one says something different than another. Not just using a different word, but in context conveys a different message.

Concerning the passage you quoted, I think the idea is about witchcraft and scorcery as they involve devination. Only God knows the future and He sets devination on the level of idolatry in this section. It is a serious offence to God. That doesn't mean that we are to go around killing any that portend to be withces today. Just as we do not offer burnt sacrifices in modern times.

Check out this link for a more articulate answer to the issue.

The reliability of the Bible
http://www.equip.org/free/CP1000.pdf

Reliability of the Bible manuscripts
http://www.equip.org/free/CP1001.pdf

M-A-P-S to Bible reliability
http://www.equip.org/free/DB011.pdf

How do we know the Bible is the Word of God
http://www.equip.org/free/CP1012.pdf

Choosing a Bible translation
http://www.equip.org/free/CP1006.pdf

Talk to you later friend.