The Invisible power allows owners to hide from lower ranks (i.e. owners can see other invisible owners, but cannot see invisible main owners) and still be able to see the chat messages. The power automatically works while enabled.
If you send a message in the main chat, your invisibility will be broken and users will be able to see you again. However, sending a message in a private message, private chat, or performing a chat action will not break your invisibility. To become invisible again, sign out and back in.
While on the HTML5 version of xat, it is possible to see another user's invisible pawn. This functionality does not translate over to the Flash version.