When this creature enters, exile another target creature.
When this creature leaves the battlefield, return the exiled card to the battlefield under its owner's control.
All Nightmares get +1/+1.
, 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 leaves the battlefield, exile all Nightmares.