Select 1 face-up monster with an ATK equal to 1000 points or less on your side of the field. During the turn this card is activated, the selected monster can attack your opponent's Life Points directly.
Using this card to buff up your monster that will deal the massive blow (Sacrifice other High ATK monster on your side of the field). Just be sure to use Secret Pass to the treasure first to enable that monster to attack directly incase there is a monster on your opponent's field.
A monster that is targeted by this card is still be able to conduct a direct attack even the ATK of the monster is increased to over 1000.
it can only be used when their attack is below 1000, so you have to use it first before increasing their attacks. i've used it on piranha, vassal, and unhappy girl before and there's no problem with it.