A group of players in Australia play this variation: When the trump has been declared all Wizards become that suit. This means that if Hearts are trump, for example, and a player leads a Wizard all other players must play a heart (or a jester) if they have one. If all you have in the heart suit is a Wizard then you must play it and of course it loses to the first-played Wizard.
This rule makes the Wizards far more powerful and enables a player to take control far more easily.