Pursuers of Lost Souls

You can't cast Pursuers of Lost Souls unless a creature has died this turn.
Wither (This deals damage to creatures in the form of -1/-1 counters.)
Pursuers of Lost Souls attacks each turn if able.
Morbid -- At the beginning of each end step, if a creature died this turn, create a token that's a copy of Pursuers of Lost Souls.