Ominous Lockbox
Artifact — Clue, {1}{U}
Oracle Text
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.
{2}, Sacrifice Ominous Lockbox: Draw a card.