Narule Dragon Lord of Undead

If you had payed life to cast Narule Dragon
Lord of Undead you may an emblem that is (creatures you control have undying).
Whenever a player loses life you may create a
2/2 zombie creature token.
{1}{b}: Retern target creature from a graveyard
to the battlefield under your control target player loses life equal to that creature
converted mana cost.