Kukyo, Angel of Void

Kukyo costs {1} less to cast for each 1 life your opponents have lost this turn.
As long as Kukyo is in the command zone or on
the stack, your opponents can't lose the game.
As long as Kukyo is on the battlefield, you can't
lose the game.
"You may waste away for as long as you wish. Eventually, you will perish all the same."