Lexis Advance® will accept either the * or the ! as a command to find variations of a search term. They are not exactly the same, however. If you use the ! to truncate a word, you must have at least 3 characters in front of the ! symbol. If you use the * to truncate a word, there are no such restrictions.
You can use the ? (question mark) symbol to find variations of a word by replacing characters anywhere in the word, except for the first character. You can use one ? for each character you wish to replace. For example: