Nightmare Shepherd

Flying, Mindbreak.
Whenever a non-token, non-Great-One creature you control dies, you may transform it into a Petrified Soul tokken instead of sending it to the graveyard, or create a 1/1 token copy of that creature.

Whenever a creature an opponent controls becomes tapped, put a Madness counter on it. At the beginning of each upkeep, each creature with a Madness counter on it loses life equal to the number of Madness counters on it. Whenever a creature dies due to life loss from Madness counters, its