Cannot be Normal Summoned (but can be Normal Set). At the start of the Damage Step, if this card attacked a face-down Defense Position monster: Destroy that monster, and if you do, you can place it on top of your opponent's Deck instead of sending it to the Graveyard.
The good part about this card is the effect that puts the destroyed monster on top of your opponents deck. If they had to set the card before, then it is very likely that the card isn't of use face-up. Making them draw the card again prevents them from getting a new card that can help them gain a bigger advantage or a comeback. This is one of the reasons Red Dragon Ninja was so good.