Say Your Prayers

Enchant Creature
At the beginning of each end step place an
Insanity counter on enchanted creature.
Enchanted creature gets -1/-1 for each Insanity
counter on it.
If enchanted creature were to die, instead exile it
and create an X/X black Nightmare creature
token with flying, where X is the number of
Insanity tokens on enchanted creature.
Sleep with one eye open...