不(ふ)吉(きつ)な保(ほ)管(かん)箱(ばこ)

As Ominous Lockbox enters, secretly choose a number between 1 and 20.

When an opponent casts a spell with mana value equal to the chosen number, sacrifice Ominous Lockbox. If you do, copy that spell, and you may choose new targets for the copy.

, Sacrifice Ominous Lockbox: Draw a card.