Nighthowler is a uncommon Enchantment Creature — Horror card from Pioneer Masters (PIO), collector number 98.
Bestow {2}{B}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.) This creature and enchanted creature each get +X/+X, where X is the number of creature cards in all graveyards.