Cassimolar

When this card is Normal Summoned: You can target 1 face-up monster your opponent controls; it gains ATK equal to its original ATK, also during the End Phase of the next turn, destroy that face-up monster, and if you do, your opponent takes damage equal to half its original ATK. At the start of your opponent's Battle Phase: You can Tribute this Normal Summoned/Set card; your opponent's monsters cannot attack directly for the rest of this turn.