Death, Fourth Horseman

Delve
Death, Fourth Horseman can't attack unless you have X creature cards in your graveyard (Where X is half of your life rounded up)
If your health is at five or less and Death, Fourth Horseman is on the battlefield under you control, you get an emblem with "As long as you control a black permanent, you can't lose the game."
"You can't escape me mortal."