Commander Masters

Chainer, Dementia Master

All Nightmares get +1/+1.
{B}{B}{B}, Pay 3 life: Put target creature card from a graveyard onto the battlefield under your control. That creature is black and is a Nightmare in addition to its other creature types.
When Chainer, Dementia Master leaves the battlefield, exile all Nightmares.

Dominaria Remastered

Torment

All Nightmares get +1/+1.
o
Bo
Bo
B, Pay 3 life: Put target creature card from a graveyard into play under your control. That creature is black and is a Nightmare in addition to its creature types.
When Chainer, Dementia Master leaves play, remove all Nightmares from the game.