The Mind Flayer

Menace, intimidate, protection from white and from black
Ward —Exile half your library, rounded up.

Graveyards can't be the target of spells or abilities other than the Mind Flayer's.
Whenever the Mind Flayer deals combat damage to a player, that player discards half that many cards, rounded up, then mills a number of cards discarded this way.
You may play nonland cards from graveyards by paying 3 life in addition to paying its other costs and spend black mana as if it were mana of any color t