De-Spell

''Destroys 1 Spell Card on the field. If this card's target is face-down, flip it face-up. If the card is a Spell Card, it is destoyed. If it is not, it is returned to it's face-down position. The flipped card is not activated.''

This card is useful for getting rid of Continuous, or Limited Time Spell Cards, such as Swords of Revealing Light, and Spell Absorption. However, it has an alternate use. If you want to carry out an attack, but your opponent has a card in the Spell/Trap Zone, De-Spell can be used to find out if it poses a threat. If it's just a Spell Cad, it's destroyed (and in the case of Mystical Space Tycoon, that's an added benefit). If, however, the card is a Trap Card, you can see which one it is, so you'll be able to judge whether you can either attack, or sucessfully summon a Monster (In the case of finding Mirror Force, and Trap Hole, recpectively).