Nul, Master of Codexes

Vigilance, Double Strike

CODEX OF CERBERUS—When this creature deals combat damage to a player. That player mills X cards face down. Where X is the damage dealt by Nul.

The Ronin's Echo— Spells faced down have {t}{2}{w}{u}{b}: You can cast cards from an opponent's graveyard. As long as they remain faced down.