Dominion of Shadows

Whenever you put one or more token creatures
enter the battlefield, Dominion of Shadows
deals that much damage to target opponent,
creature an opponent controls, or planeswalker
an opponent controls.
{p/b}{p/b}: create X 1/1 shadow token creature with "{t} sacrifice this creature: add one mana of any
colour" where X is the amount of damage a target opponent has taken this turn
(this ability once a turn)