Sengir Vampire | Magic: The Gathering
Formats Sengir Vampire is Legal in
Official Oracle Text for Sengir Vampire
Whenever a creature dealt damage by Sengir Vampire this turn dies, put a +1/+1 counter on Sengir Vampire.
Official Rulings for Sengir Vampire
9/22/2011 : Each time a creature is put into a graveyard from the battlefield, check whether Sengir Vampire had dealt any damage to it at any time during that turn. If so, Sengir Vampire's ability will trigger. It doesn't matter who controlled the creature or whose graveyard it was put into.
9/22/2011 : If Sengir Vampire and a creature it dealt damage to are both put into a graveyard at the same time, Sengir Vampire's ability will trigger, but it will do nothing when it resolves.