Syr Konrad, the Grim - 107 U ELD

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 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.)

uncommon
Legendary Creature — Human Knight
From the Magic: The Gathering set Throne of Eldraine.