Patapatu,dead angel

Lifelink, deathtouch,flying,when patapatu enters
the battlefield killer(Destroy {x}creatures where
{x}is the number of creatures in every players
graveyard)
{t}{b}{r}:killer
{0}:demons you control get deathtouch and flying
{t}{10}{b}{b}{r}{r}{b/r}{b/r}{p/b}{p/r}:deal 50 damage to any
target