This is the second line of defence on the edge of the castle grounds: A bunker, with water pistol-wielding guards inside, in front of and on top of it.
The contestants all have a water pistol and paper rings stuck to their helmets. On go, they all rush over to the bunker and have to climb over the top of it.
As they're climbing over, the guards will try and break the contestants' rings by shooting it with water. If a contestant's ring gets broken, they have lost and are out of the game.
The guards also have rings that the contestants can try to break. If a guard's ring does get broken they can't shoot anymore.
All the contestants that manage to get over the bunker without having their ring broken move onto the next round.