The Witch King of Angmar

Protection from Humans.
Nonlegendary creatures your opponents control
get -1/-1.
Other creatures you control have persist.
'Sauron has yet to reveal his deadliest servant, the one
who will lead Mordor's armies in war. the one they
say no living man can kill. He is the lord of the
Nazgul, greatest of the Nine.'
— Gandalf