Horseman of Death

Pay 5 Life, {b}{b}: Destroy target creature and its controller loses life equal to target creature's toughness destroyed this way.
Whenever Horseman of Death enters the battlefield, each player discards their hand then
each opponent loses life equal to the amount of
cards in all graveyard and you lose life equal
to half the amount of cards in all graveyard (If it
is odd numbers, round up)