Vampire creatures you control get +2/+0 and gain first strike until end of turn.
Many peasants secretly admire vampires' glamour and elegance—until they witness a moment of pure bloodlust.
Official Rulings for Vampiric Fury
9/22/2011 : Only Vampires you control when Vampiric Fury resolves will receive the bonus. Creatures that enter the battlefield, that you gain control of later in the turn, or that become Vampires later in the turn won't be affected.