Corpse of the Forgotten

At the beginning of each opponent's end step, if
Corpse of the Forgotten is in your graveyard,
each player loses life equal to its power.
"Sometimes, in the deepest dungeons, the jailers forget
to take away the bodies. After a year, the soul of the forgotten body will come back, wishing doom upon
those who wronged it. I will do further research into
them, for, as far as I understand, they are stronger
then others."
—Tamiyo