The object of the game is to get the most kids on your side.
This is an adaptation of rock, paper, scissors. Giants beat Trolls, Trolls beat wizards, and Wizards beat Giants.
So the big group is separated into to groups. The individual groups huddle and establish which creature they are going to be. So when the facilitator gives them the signal each team has to show their form (Giants stand up straight with arms erect to the sky and roar, trolls crouch and snicker, and Wizards flick the wrists/wands while making “ssst” sound). Which ever team wins runs and attempts to take the losing players before the losing players reach their home base.