Ghitu Journeymage’s triggered ability doesn’t deal more damage if you control more than one other Wizard.

In a Two-Headed Giant game, Ghitu Journeymage’s ability causes the opposing team to lose 4 life.

Ghitu Journeymage’s ability doesn’t trigger if you don’t control another Wizard immediately after it enters the battlefield. If it does trigger but you don’t control another Wizard as it resolves, it does nothing.