There is no reason a will needs to mention anything about "CTB". (On the other hand, if you have life insurance then oftentimes they don't pay out in the event of suicide. But I don't think that's what we're talking about here).
A properly drawn will signed and notarized in the United States should do it, but it will have to go through probate. Will still get contested, especially the more money the more "funny."
Not sure about internationally, but in the US even more ironclad would be a trust, which would avoid probate and keep all transactions private. Trust can be put together with online resources, or most attorneys will do it for a couple thousand dollars. (Recommend spending the money).