Heart of the Rot Bogs

Partner with Bitter Bones, Grafted
Defender, Ward {3}
Skeleton creatures in the graveyard have "{x}{b}: Return this creature from the graveyard to the battlefield tapped, where {x} is this creature's mana value."
{b/g}{b/g}{b/g}{b/g}: Regenerate all skeleton creatures you control, you lose life equal to the number of creatures regenerated this way.