The List

Unmask

You may exile a black card from your hand rather than pay this spell's mana cost.
Target player reveals their hand. You choose a nonland card from it. That player discards that card.

Secret Lair Drop

From the Vault: Lore

You may exile a black card from your hand rather than pay Unmask's mana cost.
Target player reveals his or her hand. You choose a nonland card from it. That player discards that card.

Mercadian Masques

You may remove a black card in your hand from the game instead of paying Unmask's mana cost.
Look at target player's hand and choose a nonland card from it. That player discards that card.