Death's Hydra

Flying, deathtouch, trample, shroud, haste, vigilance, double strike.
This creatures power and toughness is twice the number,of creatures on the battlefield.
{2}{r}{r} Destroy target creature.
{2}{b}{b} Once per turn target creature from target players graveyard,
add it to the field as a enchantment aura it is still a creature this creature gets the abilities of target card.
when this creature dies blow up every card on the battlefield