Franny, Teacher of Teachers

Indestructible
Franny is not a creature unless you have five or more creatures in your graveyard.
{b}Sacrifice a creature
On your turn, Franny deals damage to an opponent equal to the number of creatures in your graveyard
Franny's power and toughness are equal to twice the number of creatures in your graveyard.
"Oh, the fun hasn't even begun yet!" - Isaac, herald of Franny.