Cassius, Tainted Shadow

When Cassius, Tainted Shadow enters the battlefield, deal {x} damage to target non-legendary creature, where {x} is the number of creatures in your graveyard.
Shadow
Shroud
{r}{r}{g}{g}: Creatures you control gain hexproof and haste until end of turn.
Cassius, Tainted Shadow isn't a creature unless there are 7 or more creature cards in a graveyard.