Obzedat's Last Rite

(You may cast a legendary sorcery only if you control
a legendary creature or planeswalker.)
Each player loses X life and you gain X life. For
the rest of the game, whenever a creautre you
control dies, each opponent loses 1 life and you
gain 1 life.
"As our dying wish, you will all come down with us."
-Karlov of the Ghost Council