What do you think about this trap card?

[nikephorosaias]

[img]http://img651.imageshack.us/img651/5206/createcard2l.jpg[/img]

This card's activation cannot be negated. Activate when your opponent is attacking a face-up monster you control while you control 2 or more face-up monsters on the field. Banish one face-up monster you control (except the one that is being attacked), then the attacking monster loses ATK equal to the original ATK of the monster that was banished, until the end phase.

This card is meant for a game reversal, and it can be used in many ways.

[ekko1990]

Well, the cards seems pretty good, but you will have to change 1 thing. When you banish the other monster before the damage step, the number of monsters you have changes, so a replay occurs in which the opponent will stop the attack if your monster would destroy his.

You could write it like this.
"The activation of this card cannot be negated. Activate only during the damage step when your a face-up monster you control is attacked. Select 1 face-up monster you control other than the one being attacked; Banish it and decrease the ATK of the attacking monster by the original ATK of the banished monster."