Nebuchadnezzar

{X}, {T}: Choose a card name. Target opponent reveals X cards at random from their hand. Then that player discards all cards with that name revealed this way. Activate only during your turn.

Masters Edition III

{X}, {T}: Name a card. Target opponent reveals X cards at random from his or her hand. That player then discards all cards with that name revealed this way. Activate this ability only during your turn.

Chronicles Foreign Black Border

Chronicles

o
X, oc
T: Name a card. Target opponent reveals X cards from his or her hand at random. If that player does not have enough cards in hand, his or her entire hand is revealed. Opponent then discards any of those cards that match the named card. Use this ability only during your turn.

Legends

o
Xoc
T: Name a card. Opponent reveals X cards from his or her hand at random, or entire hand if he or she does not have enough cards. Opponent then discards any of those cards that match the one you named. May only use this power during your turn.

You don’t name a card until the ability resolves. Once you name a card, it’s too late for the targeted opponent to respond.

You may activate the ability only during your turn, but you may do so any time you have priority. (In other words, it’s not restricted to only the times you could cast a sorcery.)