Chainer, Dementia Master

狂気を操る者チェイナー (Chainer, Dementia Master) (ja)

Legendary Creature - Human Minion | Power/Toughness: 3 / 3 (CMC 5)
Nightmare creatures 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, Dementia Master leaves the battlefield, exile all Nightmares.