Mutually Assured Destruction

{r}{r}{r}, Sacrifice a land: Each opponent sacrifices a land unless they pay 4 life.

At the beginning of your end step, if a player paid life this turn, Mutually Assured Destruction deals 3 damage to target creature.

"Not many knew about the tunnels beneath that castle. Jareth, Thraximundar, Jiro...maybe three or four more."