Valuk, Enduring Hope

Attacking creatures you control have undying.
When a creature dies, you may pay {x}, where X
is that creature's mana value. If you do, amass X.
Remove X +1/+1 counters from a creature you
control: Return a creature card with mana value
X or less from a graveyard to its owner's hand.
Even after death, he seeks redemption.