Syr Konrad, the Grim [ELD-107]

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.

{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)