This card can be used to protect set monsters whose effects rely on being flipped face-up outside of battle, such as the Worms, Charmers and "Guardian Sphinx", or simply just to protect them as fodders for the next turn.
Another idea is to use this against an opponent who has "Red Dragon Archfiend". Its effect would destroy all your Defense-Position monsters if it destroys one of your Defense-Position monsters. So if you only have set monsters, all monsters on your side of the field will be safe from attacks. Just make sure you do not have a face-up Defense Position monster, as this will not protect it, and your monsters will be destroyed anyway. Using this, all your opponent's monsters except "Red Dragon Archfiend" will be destroyed due to "Red Dragon Archfiend's" ability and the fact those monsters cannot attack unless you have a face up Monster.