Sorin, Dueling Idealist

+2: until end of turn Sorin, Dueling Idealist becomes a 5/5 vampire with Hexproof and Indestructible then it duels a creature
-3: destroy target creature that Dueled this turn you may activate this ability on an opponents turn, if you do it cost 4 loyalty counters
-10: create 5 2/2 black vampires then those creatures duel 5 other creatures and you gain life for each creature destroyed at the end of this turn