Play this card immediately after taking damage from an attack. Your opponent discards the top 3 cards from his Life Deck.
There's a good chance you could have put this hand to good use.
Errata:
Whenever you take damage from one of your opponent’s attacks, you may place this card directly into play from your hand. You can only use it during your Attacker Attacks phase like a regular Non-Combat card to make your opponent discard the top 3 cards of his Life Deck.