Avaera, Leviathan Mother

Indestructible, Trample
Avaera, Leviathan Mothers power is equal to
the total power of creatures on the battlefield, its toughness is equal to the total toughness of
creatures on the battlefield plus 1.
{2}{u}{b}{g}, sacrifice a creature: Put a creature from
your hand onto the battlefield, you may only use
this ability at any time you could cast a sorcery
and only once per turn.