Corpse Traders

Oracle Text

2B, Sacrifice a creature: Target opponent reveals his or her hand. You choose a card from it. That player discards that card. Activate this ability only any time you could cast a sorcery.

Card Rulings

5/1/2012 You can sacrifice Corpse Traders to pay the cost of its ability.
4/15/2013 If you cast this as normal during your main phase, it will enter the battlefield and you’ll receive priority. If no abilities trigger because of this, you can activate its ability immediately, before any other player has a chance to remove it from the battlefield.