Dimir Crab

When Dimir Crab comes into play, target opponent mills cards equal to {x}
{u/b} Dimir Crab becomes a 1/3 crab until end of turn
{u/b}{u/b} Dimir Crab becomes a 2/2 crab until end of turn
{u/b}{u/b}{u/b} Dimir Crab becomes a 3/1 crab until end of turn