Krrykyt, Lord of the Unknown

Haste, Wither

Other Nightmares you control have wither.

Whenever a creature with a -1/-1 counter on it dies,
reveal the top card of your library. If the revealed
card is a Nightmare or Enchantment card, you may
put it onto the battlefield. If you don't, put that card
into your graveyard.

"The unknown holds the greatest nightmares"