A not so surreptitious version of the Mysterious Challenger?
Card type: Minion
Mana cost: 4
Attack: 3 HP: 4
Card text: Battlecry and Deathrattle: Put a Secret from your deck into the battlefield.
On one hand, this card could be annoying to play against. On the other hand, seeing this card played on Turn 4 instead of Call to Arms will be the lesser of two evils.