Magic The Gathering M13 Core Set Spoiler - Nefarox, Overlord of Grixis

Nefarox, Overlord of Grixis - #103/249 - Rare
Legendary Creature - Demon

Flying
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)

Whenever Nefarox, Overlord of Grixis attacks alone, defending player sacrifices a creature.

Illustrator: Aleksi Briclot

Source: Wizards