Guiltfeeder
Creature — Horror
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever this creature attacks and isn't blocked, defending player loses 1 life for each card in their graveyard.
Mark Tedin
World Championship Decks 2003 (WC03)
• #pk68sbRulings
An ability that triggers when something “attacks and isn't blocked” triggers in the declare blockers step after blockers are declared if (1) that creature is attacking and (2) no creatures are declared to block it. It will trigger even if that creature was put onto the battlefield attacking rather than having been declared as an attacker in the declare attackers step.
(wotc • 2013-04-15)
Rulings
An ability that triggers when something “attacks and isn't blocked” triggers in the declare blockers step after blockers are declared if (1) that creature is attacking and (2) no creatures are declared to block it. It will trigger even if that creature was put onto the battlefield attacking rather than having been declared as an attacker in the declare attackers step.
(wotc • 2013-04-15)