Vathys, Titan of Grasping Tide

When Vathys enters the battlefield, sacrifice it
unless it escaped.
Whenever Vathys enters the battlefield or attacks,
each player mills 2, then you may have target
creature get -X/-X where X is the number card
types among cards in its controllers graveyard.
Escape—{u}{u}{b}{b}, Exile five other cards from
your graveyard.