Time Marches on...

Whenever a non-token creature would die, its
controller may pay 2 life. If they do, exile it
instead and they create a 2/2 black Zombie
creature token.
{w}{u}{b}, Pay X life: Create a token copy of target
creature exiled with Time Marches on..., except
it's a black Zombie in addition to its other types.
X is the toughness of the creature. Use this
ability only once each turn.
But there ain't no rest for the wicked.