When hit the helmet quacks, attacker loses next turn because he falls on the ground laughing.
When attacking an enemy the victim is tickled which diminishes his defense.
Enemy beasts perceive you as a walking meat buffet and forget the existence of any of your units except for the wearer of the cloak. They do no attack any of your other units, but go straight for the man-in-the-cloak.
Army gets water walking, at the cost of a movement point. During combat the hero is movement impaired, but all enemy units have a chance to lose their initial turn because they are too busy laughing.